Rabbi Dayan’s shiur was planning a Chanukah mesibah together with their rebbi. Zvi volunteered to oversee the logistics and assign each talmid something to bring for the mesibah.
Zvi figured one-half to one-third bottle of soda per person, so he planned 12 bottles for the 30 students. Reuven was assigned to bring a six-pack of Coke or Pepsi and Shimon a six-pack of Sprite.
Reuven arrived early with his six-pack of Coke. Other talmidim brought doughnuts, latkes, paper products, etc. They were about to begin the mesibah, when Zvi received a message from Shimon that something urgent came up and he would be able to come only at the very end of the mesibah.
Zvi realized that Reuven’s six bottles would hardly suffice. He ran to the store across the street and bought a six-pack of Sprite.
Toward the end of the mesibah, Shimon arrived with his bottles of Sprite. “Glad you were able to make it!” Zvi greeted him. “We don’t need your Sprite anymore, though. I bought a six-pack at the beginning, and we’re wrapping up now.”
“Then I have to pay you,” said Shimon. “I was supposed to bring the Sprite!”
“But you bought already,” said Zvi. “I can’t expect you to pay double. I decided on my own to buy the additional bottles.”
“But you simply bought what I was supposed to bring,” insisted Shimon. “Why shouldn’t I have to repay you?”
“We can ask Rabbi Dayan,” suggested Zvi.
Zvi and Shimon approached Rabbi Dayan, and asked:
“Does Shimon have to pay Zvi for the additional bottles?”
Rabbi Dayan explained, “The Mishnah (Kesubos 107b) teaches that if a man left town and another person sustained the man’s wife on his own initiative, without stipulating that it was a loan to her, that other person does not have a halachic claim against the husband upon his return” (E.H. 70:8).
“Rabbeinu Tam (Tosafos ibid., s.v. ‘ha’) explains that this is because had the other person not sustained the wife, she could have managed in some other way or eaten less. However, he maintains that this does not apply to one who paid another person’s debt of his own initiative, since this obligation is definite” (Sma 128:3).
“Other Rishonim, though, maintain that this halacha applies also to someone who pays another person’s debt on his own initiative, since the borrower might have convinced the lender to forgo the debt, or found someone else who would agree to pay it (Shach 128:4).
“Shulchan Aruch and Rama rule that it applies also to other debt, while some Acharonim leave the issue undecided or make various distinctions” (see Shach 128:5).
“Had Zvi not bought the bottles to cover’s Shimon’s responsibility, the class would have managed without the extra soda, and Shimon would not be under any debt. Thus, this case seems similar to the Gemara’s case (one who sustained another’s wife), so that seemingly Shimon should not be liable even according to the second opinion.
“Nonetheless, since Shimon initially bought the Sprite for the class, if he retains it for himself, he should pay them for the bottles“ (C.M. 183:4; see Igros Moshe C.M 1:48).
“Moreover, the talmidim of the class are all considered partners in covering the mesibah’s costs. This seems true even though each member of the class was assigned to buy something specific. Partners have a different rule, and one partner who laid out money for the partnership’s need, or who paid of his own initiative a debt of the partnership, is entitled to reimbursement from the other partners, even without their explicit directive” (C.M. 77:1).
“Thus, although had Zvi not bought additional drink the class would have had to manage without, since the talmidim are all considered partners, when Zvi spent to cover Shimon’s share of the partnership, he is entitled to reimbursement.
“Thus,” concluded Rabbi Dayan, “Shimon must reimburse Zvi what he laid out to cover the additional bottles.”
Verdict: A person who pays another person’s debt of his own initiative has no halachic claim according to many poskim, but a partner who paid the partnership’s debt does.