A tradesman who resides outside of a town where his type of business has already been established can be barred from plying his trade in that town.
Rav Dimi, a Sage, brought his figs to a town that wanted to give him exclusive trading rights. They sent Rav Adda bar Abba to test him. He asked, "If an elephant swallows a willow-reed basket and then ejects it through its rectum, is it susceptible to ritual impurity, or is it like manure? Rav Dimi didn't know, so Rav Adda patronized him. Rav Dimi's figs spoiled, and Rav Adda died. Every Sage involved took the blame for Rav Adda's death on himself – because they wanted to discharge their karmic debt.
One who builds a wall opposite the windows of his neighbor's house must ensure that the wall is either higher or lower than the windows so that he can't stand up on it or hang from it to look inside.
Art: The 'Ma Roberts' and an Elephant in the Shallows, Lower Zambezi by Thomas Baines