Pesachim 32 - Eating priest’s chametz
If a wall fell on one’s chametz and buried it, he is not required to dig after it in order to destroy it. However, he still needs to renounce it in his heart - lest it becomes uncovered during Passover and he will want it. How deep does it have to be buried? - So that a dog cannot dig it out. And how deep is that? - Three handbreadths.
If one eats the priest’s portion (terumah) on Passover, and it was chametz, then if he did it by mistake, he needs to repay the amount he ate plus one fifth, whereas if he did it on purpose, he needs to repay nothing at all.
This seems counterintuitive! However, let’s look deeper. If he eats terumah (2% of the crop, Kohen’s portion) by mistake, then the Torah says that he needs to return the grain itself. The grain becomes terumah again, and he even adds one-fifth in order to be forgiven for his error.
By contrast, if he eats it knowingly, then he is treated like a regular thief, who repays only what he has stolen, in cash or in other goods. Since chametz on Passover is worth nothing, it turns out that he stole zero value and has to repay zero.
Art: Peasants eating in a farmyard by Antonio Diziani