Nedarim 33B

דברי חנן היא.

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.

רבא אמר: אפילו תימא דברי הכל, גבי מודר הנאה דיהיב על מנת שלא לפרוע.

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.

מאי חנן? דתנן: מי שהלך למדינת הים, ועמד אחד ופירנס את אשתו. חנן אמר: איבד את מעותיו.

The Talmud asks: What is the opinion of Ḥanan to which the Talmud referred? The Talmud answers that it is as we learned in a Mishnah: 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.

נחלקו עליו בני כהנים גדולים, ואמרו: ישבע כמה הוציא, ויטול. אמר רבי דוסא בן הרכינס כדבריהם. אמר רבי יוחנן בן זכאי: יפה אמר חנן, הניח מעותיו על קרן הצבי.

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. R' Dosa ben Harkinas said in accordance with the statement of the sons of High Priests. R' 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.