Zevachim 7 – Thanksgiving Offering Slaughtered as a Thanksgiving Offering of Another

What happens when a Kohen slaughters a thanksgiving offering of one person for the sake of thanksgiving of his fellow? This does not mean that he wants the sacrifice of one to become the sacrifice of the other! That would a simple case of change in the ownership of the sacrifice, and it would not be credited to its owner. Rather, the Kohen meant that the offering of one owner should assume the sacred properties of another one, but still belong to the first owner.

Rabbah said that it is valid: all thanksgiving offerings are the same, even those of different people. Rav Chisda said that it is invalid: each person's thanks are different - for example, one may be thankful for successfully crossing the sea, while the other one – for being released from prison. This leads to a change in holiness, making the sacrifice not valid for its owner. The argument remains without a clear winner.

Art: Francisco De Goya y Lucientes - Prison Scene