For the source text click/tap here: Nedarim 85
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It was taught in a braisa: If one steals the tevel (untithed produce) of his fellow, he is obligated to pay him for the value of the entire tevel (including the terumah and ma’aser that is mixed in, according to its value to him based upon his ability to choose who he wants to give them to).
Rabbi Yosi the son of Rabbi Yehudah says: He is obligated to pay him only for the value of the chulin. It must be that Rebbe holds that the benefit of gratitude has a monetary value, while Rabbi Yosi holds it does not. The Gemora rejects this and gives an alternate explanation to their argument. Everyone agrees that the benefit of gratitude does not have a monetary value. Their argument is whether we view the amount of grain that must be tithed as regular grain, or we subtract its value from the rest of the grain, as if it is has already been given.
This leads us to explore the notion of gratitude from a philosophical and Judaic perspective.