Talmud - Nedarim 33b נדרים ל״ג ב׳

is the statement of Ḥanan in a dispute pertaining to one who pays the debt of another. Ḥanan holds that he cannot demand to be reimbursed for that payment, since he merely prevented potential damage.

Rava said: Even if you say that everyone agrees that this is the halakha, it was stated with regard to one prohibited by vow from deriving benefit from another who borrowed money, and the creditor stipulated that it was on the condition that if he so chooses he does not need to repay the loan. In that case, by repaying the loan, one who vowed and imposed the prohibition did not actually repay his debt.

The Gemara asks: What is the opinion of Ḥanan to which the Gemara referred? The Gemara answers that it is as we learned in a mishna: In the case of a husband who went to a country overseas, and one other man arose and supported his wife on his own initiative and then demanded to be reimbursed for that support when the husband returned, Ḥanan said: The one who took the initiative to support the wife lost his money, since the husband neither asked him to do so nor committed to compensate him.

The sons of High Priests disagreed with him and said: The one who took the initiative to support his wife will take an oath as to how much he spent and take repayment from the husband. Rabbi Dosa ben Harkinas said in accordance with the statement of the sons of High Priests. Rabbi Yoḥanan ben Zakkai said: Ḥanan spoke well, as in any case of this type he placed his money on the antler of a deer, i.e., a risky venture with no guaranteed return.

The Gemara explains the dispute between Rava and Rav Hoshaya with regard to attribution of the mishna: Rava did not say that the mishna is in accordance with the opinion of Ḥanan, as did Rav Hoshaya, and he preferred a different explanation, as he establishes the mishna in accordance with the statements upon which everyone agrees, rather than attributing it to an individual tanna. Rav Hoshaya did not say that the mishna is in accordance with the opinion of all the tanna’im as did Rava, as there is basis to issue a rabbinic decree prohibiting repayment of a loan for one for whom benefit from another is forbidden by vow on the condition that he does not need to repay the loan, due to a standard loan that he is required to repay. Therefore, he prefers to establish the mishna in accordance with the opinion of Ḥanan.

§ We learned in the mishna: He returns his lost item to him. Rabbi Ami and Rabbi Asi disagree about this. One said: They taught this only in a case where the property of the one returning the lost item is forbidden to the owner of the lost item, as when he returns it to him he is returning to him something of his own and is not giving him anything new. Consequently, returning a lost item in no way violates the vow. However, in a case where the property of the owner of the lost item is forbidden to the one returning the lost item, he may not return it to him, as in that case the owner indirectly benefits the one returning the lost item by enabling him to acquire the peruta of Rav Yosef. Rav Yosef said that the legal status of one tending to the return of a lost item is like that of a paid bailee. Since one who is engaged in a mitzva is exempt from performing another mitzva, while he is tending to the lost item he is exempt from giving charity to a pauper. Since the one returning the lost item profits from engaging in the return of the lost item, it is prohibited for him to do so, as he is prohibited by vow from deriving benefit from the owner of the lost item.

And one said: Even in a case where the property of the owner of the lost item is forbidden to the one returning the lost item, he returns it to him. And with regard to the concern due to the peruta of Rav Yosef, it is not a concern because it is uncommon for a pauper to happen upon a person just when he is tending to the lost item. Therefore, it cannot be said that there is profit in the return of a lost item.

Traduction : The William Davidson digital edition of the Koren Noé Talmud, with commentary by Rabbi Adin Even-Israel Steinsaltz.

Nedarim 33b explores whether one who pays another's debt or supports his absent husband's wife can demand reimbursement under Jewish law.