Taanit 31 - How to celebrate Tu B'Av

The day of Tu B'Av was celebrated as follows: the maidens of Jerusalem would go in the orchards to dance and find their future husbands.

Every girl wore a dress that she would borrow from someone else. The daughter of the King - from the daughter of the High Priest. She, in turn, borrowed from the daughter of the vice-priest. All others borrowed from each other - not to embarrass ones who did not have a beautiful dress.

Lovely girls said that "A wife is only for beauty." Those of great lineage claimed that "the wife is only for children." The good-charactered said: "A good woman, who can find her? Give her the fruits of her hands and let her deeds praise her." Each group proved their point of view with phrases from the Scriptures.

Those who lacked exceptional merit would point out that it all depends on marrying with altruistic intentions. They also added that jewelry and attractive clothing will compensate for the lack of natural beauty.

Art: A girl in a picture frame by Rembrandt

Taanit 30 - The good things of Tu B'Av

Just a few days after Tisha B'Av (ninth of the month) comes the joyous Tu B'Av (fifteen of the month.) Five good things happened on that day.

The Jews who were dying in the desert for forty years stopped dying on this day.

The prohibition to give wives to the Binyamin tribe - which resulted from the incident at Givah - was annulled on that day, and Jews were reunited.

The prohibition to go to Jerusalem, established by Yaravam ben Nevat, was removed.

The slain people of Bethar, who were killed on Tisha B'Av, were allowed to be buried. This happened on Tu B'Av, three years later. The other miracle was that the bodies did not decompose.

Art:  A Jewish Wedding by Joseph Israëls

Taanit 29 - What happened on Tisha B'Av

The five events that happened on the ninth of Av are these.

On this day, the spies came back from touring Israel. They brought a negative report, and the community cried over the seeming impossibility of conquering the Land of Israel. It was decreed that all adult male Jews of the generation would die in the desert in the upcoming forty years. The story here was that "You cried for nothing? You will have something to cry about." The Talmud calculates how the spies returned precisely on the ninth of Av.

Both the first and the second Temples were destroyed on the same calendar day, the ninth of Av. 

The city of Bethar was conquered fifty-two years after the destruction of the Second Temple. All of its inhabitants were massacred. At this time, death was decreed on the leader, Rabban Gamliel. The Roman messenger appointed to bring about Raban Gamliel's execution was a secret admirer of him. The Roman tradition was that if the messenger dies, the decree is annulled. The messenger threw himself from the roof and died, thus saving Rabban Gamliel.  The Heavenly voice announced: this Roman official has earned his share in the World to Come.

Art: The Death of Chatterton by Henry Walli

Taanit 28 - The fast of the seventeenth of Tamuz

On the seventeenth of the month of Tamuz, five bad things happened in Jewish history, and five other things happened on Tisha B'Av. Both days are commemorated by fasting. These days are three weeks apart; Lamentations hints at this by saying, "All her pursuers overtook her within the straits." What are the five bad things?

Moses broke the Tablets of the Covenant. The Talmud makes the calculation: Moses went up the Mount Sinai and got the Tablets, spent forty days learning the Torah, and came down when he heard the Jews worshiping the Golden Calf. This day was the seventeenth of Tamuz. 

Other events were: the invading Roman army breached the walls of Jerusalem; a Greek general, Apostumos, burned the Torah scroll written by Ezrah the Prophet and put idols in the Temple.

Art: The Siege and Destruction of Jerusalem by the Romans by David Roberts

Taanit 27 - Community standing by

The Temple service and the sacrifices were on behalf of everybody. Can people go about their business as if nothing is happening? For that reason, the appointed members of the congregation were doing "maamadot" or "standing by" - as community representatives.

Now, the whole procedure was as follows. When the appointed week for each priest group would come, they would go to the Temple. However, half of them went to the labor market in Jericho to do agricultural work, which was plentiful and provided sustenance for the priests who served in the Temple. Some say that they would change after three days so that everybody would get a chance for Temple service. There were twenty-four groups of priests in total, and thus they would serve in the Temple two weeks a year on average.

The community representative would be standing by, saying prayers, reading from the Torah, and fasting. Some were in Jerusalem, but some remained in their cities, collecting themselves in the synagogue. Each group was essential, and the sacrifices could not be brought if it was missing.

The Temple service was what assured the existence of Heaven and the Earth. What is the source for this? In the phrase, "Whereby shall I know that I will inherit Israel?" The complete conversation went like this. Abraham said, "Master of the Universe! All is well now, but if Jews sin, will you destroy them?" God said, "No." Abraham continued, "How do I know?" God said, "Take three calves and three goats, etc." This means that the merit of the sacrifices will atone." 

Art: Weaning the Calves by Rosa Bonheur

Taanit 26 - When to stop fasting?

If people were in the middle of a fast, and the rain they were asking for did fall out, they could say that it fell in their merit and stop fasting.  There are multiple opinions on this, but the story of Shmuel the HaKatan represents one extreme. (He called himself HaKatan, the Small One, although he was the most excellent sage of the generation.) 

Once, the rain fell before the daybreak. People felt tremendous, but Shmuel said it was similar to a master who said, "Give them whatever they ask, but let me not hear their voices." Another time, rain fell after the end of the fast. People felt good, but Shmuel told them it was similar to a master who said, "Wait till my servant is humbled enough and only then give him what he needs." If so, when should the rain start to be considered good, according to Shmuel? He answered, "When the prayer leader says, "Who makes the wind blow"  - and the wind blows. Then, the prayer leader says, "Who makes the rain fall," and the rain falls.

The Talmud enumerates the rules of communal worship, days of fasting, and days of feasting. When the Temple was in existence, groups of priests served on appointed weeks. Community representatives were also there, in the Temple or their cities, as if standing by their offerings. These were called "maamadot" or "standing." The saddest day of the Jewish calendar is Tisha B'Av, and the most joyful days are Tu B'Av and Yom Kippur. The following pages will give more details.

Art: The Yerres,  Rain by Gustave Caillebotte

Taanit 14 - Distresses other than drought

There was once general affliction in the Rabbi Yehudah the Prince (the grandson the compiler of the Mishnah by the same name.) Rabbi Yehudah decreed the thirteen fasts, but they were not answered, and the affliction did not stop. Rabbi Yehudah considered decreeing more fasts, but Rabbi Ami stopped him. Rabbi Ami quoted the rule, "we do not put more burden on the congregation than they can bear."

Some people dissented from Rabbi Ami and said that in his decision, he acted for personal reasons. What about the rule that Rabbi Ami quoted? They said that rule applied only to drought, but they could keep fasting for other afflictions until they were answered. 

So, did Rabbi Ami simply make a mistake? - No! There were two opinions on this in the earlier times. Rabbi Yehudah the Prince reasoned that they should not burden the community with more than they could bear. The opposing opinion said that it only applied to drought because after the time it took to go through thirteen fasts, it was already spring, and the rains would not be beneficial anyway. That is why they would stop fasting. The final, practical conclusion follows this opposing opinion. (Still, today, there are no courts that declare congregational fasts.)

Art: The Court by Jean-Louis Forain (1852-1931)

Taanit 25 – Rabbi Chanina ben Dosa

Earlier, we mentioned that the High Priest's prayer was no match to that of Rabbi Chanina ben Dosa. In his merit, the world was sustained, but Rabbi Chanina himself only had a bag of carob nuts a week. His wife was embarrassed by their poverty and would put smoking wood into her empty oven on Friday. Once, her neighbor decided to check what she was baking – since she knew that they had nothing – and knocked on the door. R. Chanina's wife hid inside. However, the neighbor saw an oven full of bread and called – "Your bread is being burned, bring a shovel!" R' Chanina's wife replied that she went for the shovel herself. This was actually true since she was used to miracles.

Another time, however, she said life was too hard and asked Rabbi Chanina to pray. A golden hand appeared and gave him one leg of a golden table. However, Rabbi Chanina was shown a dream wherein the World to Come all were eating at a three-legged table, but the table of his wife and him only had two. She asked him to pray again, and the leg was taken back.

Once, R' Chanina's daughter was sad: she put vinegar instead of oil into the Shabbat lamp. However, R' Chanina commented: the One who made the oil burn can command the vinegar to burn, and so it was: vinegar lamp burned till the end of Shabbat.

Rabbi Chanina had some goats, and the neighbors claimed that they were ruining their fields. Rabbi Chanina said, "If they do – they should be eaten by bears, but if not – each should bring a bear on her horns," Indeed, each goat brought a bear on its horns.

Art: Dancing Bears by William Holbrook Beard

Taanit 24 - Prayer and the natural order of things

Rabbi Mani was a student of Rabbi Yitzhak ben Eliyashiv. Once Rabbi Mani complained that his wife's family members were wealthy, haughty, and mistreated him. "Let them become poor," said Rabbi Yitzhak, and they became poor. Rabbi Mani complained that they were forcing him to work, and Rabbi Yitzchak said, "Let them become rich again," and they become wealthy. Rabbi Mani also mentioned that his wife was homely. "What is her name?" asked Rabbi Yitchak. - "Channa." "Let Channa become beautiful," - said Rabbi Yitzhak. And she became beautiful. But now, she became haughty and ruled over Rabbi Mani, so Rabbi Yitzhak said, "Let Channa return to her homeliness." Later, students of Rabbi Yitzhak asked to pray so that they would become extra bright. He answered, "I don't do such things any longer."

Rabbi Yose from Yukrat has a son who supervised his workers. Once Rabbi Yose was late with the worker's food, the son said, "O fig tree, bring forth your fruit for the workers to eat." When Rabbi Yose arrived, he apologized for being late since he was busy with a mitzvah. They said, "No need to worry." They told him what happened, and he said to his son, "You caused the tree to bring fruit before its time; may it be that you will pass before your time." He also had a gorgeous daughter. Once he saw a man making a hole in a wall to see his daughter. He asked what the man was doing. The man replied that he did not merit to marry her, but at least was it forbidden to look? Rabbi Yose said to his daughter, "Since you are the cause of the people stumbling, may you return to dust." Rabbi Yose's student deduced from here, "If he does not have pity on his son and daughter, I am in danger!" - and left.

Rava decreed a fast, but the rain did not come. They told him, "When Rav Yehudah fasted, rain would always come." Rava agreed. He said, "When he took off one shoe, it already rained." What is this story? Rav Yehudah once saw people throwing bread. He said, "Better there should be a famine," and so it was. The Sages asked his assistant, Rav Kahana, to take him into the market. Rav Yehudah saw a long line and asked, "What is this?" Rav Kahana told him, "People line up for flour from date pits." Rav Yehudah said, "It must be that a famine came; we need to proclaim a fast." On strict fasts, wearing leather shoes is prohibited, and Rav Yehudah asked his assistant to remove his shoes. As soon as the first one was off, the rain came. Elijah, the prophet, rushed to say, "Do not take off another shoe, or else God will destroy the world." But often, owing to the extreme shame and humiliation of the Sages who could not bring the rain, the rain would indeed come.

Art: Study Of A Fig Tree by John Singer Sargent

Taanit 23 - Choni the circle maker

Once the rains were very late in coming, and people asked Choni to pray for rain. He told them to hide away their clay ovens intended for the coming Passover sacrifice - for they would melt -  prayed for rain, but it did not come. Choni then drew a circle and swore that he would not leave it until his prayer was answered. A slight drizzle started to trickle. "This is not what I asked for," - said Choni - "but a powerful rain!" Immediately it started raining with force, and each drop was like a bucket. "That is not what I asked," - said Choni - "but a normal beneficial rain." A medium rain started to fall - but it would not stop! People collected on the Temple Mount because of the water and asked Choni to pray to stop the rain. He replied, "It is not proper to ask God to stop a blessing, even if it is too much of it."

Nevertheless, he said, "Bring me a bull for a sacrifice." He took the bull, put his two hands on its head, and said, "Master of the world, your children cannot stand too much bad or too much good." The wind blew, the sun showed, and the rain stopped.

All his life Choni was bothered by the phrase, "When we came back from Babylon to rebuild the Temple, we were like dreamers." This exile lasted for seventy years, but can anyone sleep for that long? Once Choni saw a man planting carob trees. The man told him that he was producing for his grandchildren, just as his grandfathers planted for him, for it takes seventy years for a carob to grow. Choni then sat down to eat and fell asleep. When he awoke, he saw a man by the carob tree who told Choni that he was a grandson of the man he had seen earlier. Choni deduced that he had slept for seventy years. He went to the study hall, where he heard the students say, "Today all is clear to us, just like in the days of Choni, the circle maker." He said, "I am Choni." But they did not believe him and did not pay him proper respect. He prayed for mercy and died.

Art: A man asleep on a table by (after) Arie De Vois

Taanit 22 – Military mistake of Yoshiyahu

The merit of the righteous people protects those around them. Rabbi Beroka once asked Elijah the Prophet, “Who in this marketplace deserves to be in the World to Come right now?” Elijah pointed out a Jewish man who was wearing non-Jewish clothes. Rabbi Beroka asked him what he did, and the man told him to come tomorrow. On the next day, the man said that he was a prison guard and kept particular watch over Jewish female prisoners so that they would not be violated. He would also inform the Sages of any evil designs he heard about, and the Sages prayed and annulled them. The previous day, he was rushing on just such a mission.

Then Elijah pointed out another two people. They were jesters, and when they saw anybody looking depressed, they would not let him go until he laughed and felt better. They would similarly make peace in cases of feuds.

Courts would proclaim a fast when a military force passed through even without the intent of making war on Israel -  because of a high potential of confrontation. Here is a related story. Pharaoh Necho passed through Israel, and king Yoshiyahu decided to confront him. His logic was based on this phrase in the Torah, “A sword will not pass through your land,” and besides, Necho was trusting in his idol. Nevertheless, Yoshiyahu died in battle. Why was the righteous Yoshuyahu punished? – Because he did not consult Jeremiah, and thus did not know that his generation was not worthy of Divine protection and that the phrase did not apply.

Art: A Jester by Philipe Mercier

Taanit 21 – That, too, is for the best

Nachum ish Gam Zu was called this way because he was accustomed to saying, "That, too, (gam zu) is for the best." Once the Jews needed to send a gift of precious pearls to the Roman emperor. They chose Nachum ish Gam Zu because "he is used to miracles happen on his behalf." On the road, people at an inn exchanged the precious stones in his chest for dirt from the house. In the morning, when Nachum saw it, he said, "This, too, is for the best," and continued on his way to present it to the emperor. When the latter saw the dirt, he was enraged, "Jew are mocking me!" and decided to kill them all. Nachum said, "That, too, is for the best."

Elijah the prophet appeared, looking like one of the court nobles, and suggested, "Perhaps this are magical dirt, which Abraham used to conquer his enemies." They tested the dirt in a far-away war, and the dirt turned into swords, the straw in it – into arrows, and they have successfully concluded the war. Upon return, they filled Nachum's chest with treasures as a sign of gratitude.

When Nachum returned to the same inn, the people saw the honor awarded him and asked him why. He told them the story. They razed the house, took the dirt from it, and presented it to the emperor, saying, "Nachum's dirt is from the same house." However, their dirt did not test as well as Nachum's, and they were executed.

Art: Treasures In The Granovitaya Palata by Konstantin  Egorovich Makovsky

Taanit 20 – Better to be pliable like a reed and not hard like a cedar

They declare a fast when it rains disastrously in one city, but it is a drought in another one. In analyzing this phrase from Amos, Rav Yehudah said – it is a bad sign for both.

However, on other occasions, Rav Yehudah found good signs within bad ones. For example, “Jerusalem will be like a widow.” – but not really a widow, rather, like a woman whose husband went overseas but plans to come back. Another case: prophet Achiya cursed Israel that God would smite it like a reed. And yet, reeds straighten out after a storm. On the other hand, Bilam blessed them to be like a tall cedar that withstands a strong wind. A strong wind – yes, but not a hurricane when cedar becomes uprooted. Thus, it is better to be pliable like a reed and not hard like a cedar. Moreover, the reed merited that a pen is made from it.

Rabbi Elazar, son of Rabbi Shimon, was going home from his yeshiva on a donkey, and he was happy about the Torah that he had learned. A hideous man greeted him, but he replied, “How ugly is that man!” The man said, “Go back to the craftsman who made me and complain to him.” Rabbi Elazar immediately got down from the donkey and started begging forgiveness, but the man was adamant. Only when the people of the town to which they were going interceded did the man grant forgiveness. Rabbi Elazar directed to the study hall, and his first lesson was, “A person should be pliable as a reed and not hard as a cedar.”

Art: Reeds in Shallow Water by Paul Baum

Taanit 19 – Nakdimon Ben Gurion

The series of fasts that we have spoken about earlier are only for rains that are coming late. The rationale is that this is a gradual worsening of the situation, which can be fixed. However, for serious calamities they fast and cry out right away. What is considered a serious calamity? If the crops grew abnormally and may be totally ruined, if the rains fell irregularly (too strong or too weak), or any other natural or economic condition which may result in a dangerous food shortage.

Once all Israel collected in Jerusalem for a Festival, but, due to a drought, there was not enough water for them to drink. Then Nakdimon ben Gurion, a very wealthy Jew, went to a Roman patrician to borrow twelve wells of water. He promised to return the water by way of rains, and if not – to pay twelve talents of silver (equal to about seven million dollars). The promised day has come, but there was no rain. Thrice did the patrician send for his money, but Nakdimon argued that he still had until the end of the day. Then the patrician went to the baths, preparing to celebrate, while Nakdimon went to the Temple to pray. He said, “You know, God, that I did not do it for my own – or my family's – glory,” and the rains poured. And yet, the patrician claimed that the rain came after the sun was down. So Nakdimon went back to the Temple to pray, and the sun has shown through the clouds.

In general, the sun stood still for three people: Moses, Joshua, and Nakdimon.

Art: Cloudy Skies, Sunset, Jamaica by Frederic Edwin Church

Taanit 18 – Miracles and fasts

Several miracles happened to the Jews during the Second Temple, and “The Scroll of Fasts” records when one is not supposed to fast or eulogize the dead because of the miracles that happened on these days. First, the Talmud deals with the details of these prohibitions and then describes the miracles.

The daily sacrifice in the Temple has to be brought from communal funds, but the school of Sadducees argued that it should be brought by an individual. The argument lasted for eight days, from the first of Nissan, and the Sages convinced their opponents. This was considered a miracle.

The school of Baitus about the date of Shavuot: they understood the word “Shabbat” as Saturday, but the Sages had the tradition that in this context, it means a Holiday of Passover. Again, the Sages convinced them, and this miracle was celebrated for all the days when the argument occurred.

A Greek governor Nikanor would wave every day toward the Temple, saying, “When will it fall into my hands, and I will trample it?” When the Maccabees prevailed, they cut off his thumbs and big toes and hung them at the gates of Jerusalem, saying, “The mouth that said it, the hands that waved and the feet that would trample – let revenge be taken against them.” Incidentally, they cut off his head, too.

Turianus accused the Jews of murdering his daughter. Two men, Lullianus and Papus, stepped up and falsely admitted the crime. Before Turianus executed them, he said, “You are from the people of Chananya, Mishael, and Azarya; let a miracle happen to you!” They answered, “They were perfectly righteous, but we are not, and Nebuchadnezzar was a proper king, but you are a commoner. However, God chose you to execute us so that He can then take revenge against you.” Turianus nevertheless killed them right away, and at that very moment, messengers arrived from Rome to execute him in turn. This happened on the twelfth of Adar.

Later all these minor holidays were abolished because of subsequent sad events that occurred on these days.

Art: Battle between the Maccabees and the Bacchides by Jean Fouquet

Taanit 17 – Why do Kohanim drink wine?

A Kohen who is drunk cannot serve in the Temple. Since the Temple can be rebuilt any day, it follows that a Kohen who knows the day when he would be officiating in the Temple should not drink wine on that day. He should also not drink wine the week that he knows would be his week to serve. And since no Kohen today knows his lineage and Temple schedule, no Kohen should ever drink wine.

However, Rabbi Yehudah the Prince says that although it is true, but what can he say – since their ruin (not being able to serve in the Temple) is also their defence: it has been many years that the Temple has not been rebuilt, and they can now drink wine any time.

But, by the same token, they should also cut their hair at least every thirty days! Why? – Because drinking wine and growing long hair are prohibited in the exact same phrase. – No, that logic is wrong! If the Temple is rebuilt, and we are looking for a sober Kohen to serve there and can find none - then indeed we are in trouble. But a long-haired Kohen can quickly take a haircut and go officiate.

Art: Elegant company drinking in an interior by Jan Olis

Taanit 16 – The sad customs

We mentioned that on the last seven fasts for rain, they prayed in the public square. Why would they do this? – To show that "We prayed in private, and it did not help. Now we humiliate ourselves in public." Others say that it is to exile ourselves since an exile expiates the person's wrong deeds. What is the practical difference between the two explanations? According to the second one, we would be able to "exile" ourselves to another synagogue, but only a public place would suffice, according to the first one.

On fast days, people visited cemeteries to show that "We are considered like dead before God." Others say that it is to influence the dead so that they should pray on our behalf. What is the practical difference between these two explanations? According to the first one, any cemetery will do, but one needs to go specifically to a Jewish cemetery according to the second one.

A prototypical fast is the one people did in Nineveh, in the days of Jonah – except that they had different arguments. For example, they tied animal mothers and offspring separately and proclaimed, "If You, God, do not have mercy on us, we will not have mercy on them." They also argued, "The righteous usually yield before the wicked. You, God, are righteous, and we are wicked, so You should yield before us and pity us." But they also did good deeds: for example, if one of them stole a beam and built a palace for himself, he would now repay the money and dismantle his palace to return the stolen goods.

Art: Leverington Cemetery by William Trost Richards

Taanit 15 – Not everyone's prayer is equal

An important person should not "fall on his face" - prostrate himself in prayer, unless he is sure to be answered – just like Joshua did. Otherwise, his public spectacle will make him an object of ridicule, and people will doubt his inner worth.

Similarly, one should not put on sackcloth, like King Ahab did. In his case, he was answered. Here is the story: a woman was crying, asking for help from the King. He asked her what the matter was. She told him that she agreed with her friend to boil and eat her son, and then the friend's son the next day, but now the friend hid her son. When the King heard that, he was so overwhelmed with the realization of how bad the famine was that he put on sackcloth and started to pray and, even though he was not righteous, his prayer was answered in one day – flour became plentiful and cheap.

How did they conduct the seven most strict fasts? They brought the Torah into the town square. They put ashes upon the Ark, upon the head of the leading ruler, and the heads of the Court members. Then everyone else put ashes on his own head. A Sage among them tried to captivate their hearts, starting with "Brothers, remember the people of Nineveh: God looked not at their sackcloth and fast but at their good deeds and stopping to do evil."

They added six special blessings to the regular eighteen, and thus the prayer leader says the twenty-four blessings in his prayer. The extra ones deal with redemption, remembrance, and answering prayer.

Art: The Irish Famine by George Frederick Watts

Taanit 13 – Series of fasts

If the first three fasts were not answered by rain, the Court decrees three more fasts. People stop eating before sunset; all other restrictions are similar to Yom Kippur or Tisha B'Av, and even work is not allowed. If these fasts pass and still there is no rain, the Court decrees another seven fasts. On these last fasts, even stores are closed.

More than thirteen fasts for rain are not decreed on the congregation. Instead, construction and planting of joyous nature are forbidden; people reduce engagements, marriages, do not greet each other, and behave like people censured by God. After this, exceptional individuals continue fasting until the spring month of Nissan, since after that, the rain, even if it falls, is no longer a sign of blessing.

Why did the Sages prohibit work on these fast days? Granted, all other prohibitions are against enjoyment, but work is no pleasure!? They are similar to Holidays – both are called "a gathering," and just as work is prohibited on the Holidays, it must be prohibited on these stringent fast days.

Art: Morning Greeting by Daniel Ridgway Knight

Taanit 12 – Fasting for part of a day

Can one accept on himself to fast for only a part of the day? Rav Chisda said that it is impossible: it is not considered a fast if he ate before the end of the day. Then what is the concept of a partial fast? Rav Chisda will answer one who was too busy to eat in the first part of the day, and then decided to accept the fast until the end of the day: such a fast is valid, and he is even allowed to say the special prayer "Answer us!" for the fast days.

But how about the laypeople accompanying the kohanim in bringing the sacrifices – they were fasting but not completing the fast, and nevertheless, it is called a fast? – Ravi Chisda answers, "They did it just to afflict themselves, but it is not an official fast." So then what about Rabbi Yochanan, who used to declare, "I am in a fast until I come home." – He was only doing this to avoid the social obligation of a meal at the house of the ruling prince. And yet, some say that there is a concept of partial fast having spiritual significance.

Rav Yehoshua visited the home of Rav Idi, and they made a special meal for him, a calf one-third grown. He said, "I can't eat; I am fasting." They told him, "Do this: cancel this fast and repay it later!" He answered, "My fast has a reason: I saw a bad dream. In that case, you cannot change the day since the fast must be on the day of the dream." That is true even on Shabbat, except that on Shabbat, one should not fast – so what does one do? Fast now, and then fast again on a weekday, to atone for his fasting on Shabbat.

Art: Joseph's Dream By Gaetano Gandolfi