Yehuda was invited to be Shimon’s guest at the local yeshiva’s dinner. When Yehuda arrived at the dinner, he formed them that he was a guest of Shimon and he was given a seat at Shimon’s table. A year later, Yehuda received a bill for the cost of the dinner. Yehuda called the yeshiva to inquire about the charge, and the financial administrator informed him that Shimon had been delinquent on his pledges for over two years. Consequently, they were passing the cost of the dinner to his guests, since all of them had, after all, eaten a meal at the yeshiva’s expense.

Q: Is Yehuda obligated to pay for this meal?

A: One could formulate an argument in favor of the yeshiva. Rema (264:4) rules that anytime someone performs a service or favor for his friend, the friend must pay for that benefit. He cannot excuse himself from payment with the claim that it must have been done for free since he never requested the service.

This principle has a wide range of applications. One example is the case discussed in the Gemara Bava Kama (112a). A father passes away while in possession of a borrowed cow. His adult children, unaware that this cow is borrowed, figure that it belongs to their father, and they slaughter it and eat the meat. When it is later discovered that the cow belongs to someone else, they are obligated to reimburse the owner at a discounted rate (two-thirds the market value of the meat). The basis for paying a discounted rate is because we are obligating them for the benefit they had from the cow. Based on this principle, it would seem as though Yehuda should have to pay for the meal.

There is, however, a fundamental limitation to this rule. The principle applies only when there was no existing agreement between the two parties. Barring any agreement between parties, the beneficiary must pay for whatever benefit he receives even if it was not authorized. In our case, there was an understanding between Yehuda and the yeshiva that Yehuda was not going to pay for the meal. Consequently, the yeshiva may not charge Yehuda for his meal even though Shimon was negligent in paying his commitments.