2) HALACHAH: WHAT MAY A BORROWER SAY TO THE LENDER AFTER HE RECEIVES THE LOAN?
OPINIONS: The Gemara quotes Rebbi Shimon bar Yochai who says that when a person who receives a loan does not normally volunteer a greeting to the lender, he is forbidden to start greeting the lender because doing so would be a form of Ribis.

Does this mean that a borrower is not allowed to thank a lender for the loan, since his words of thanks are only because of the loan?

(a) The SHULCHAN ARUCH HA'RAV (Hilchos Ribis 9) writes that a borrower may not thank a lender or indicate in another way that he is grateful to him for the loan, or give him a blessing. Based on this, the BRIS YEHUDAH (ch. 10, note 107) rules that a borrower may not say "thank you" to his lender. He suggests, however, that a borrower may say "Tizkeh l'Mitzvos" -- "You should merit to perform Mitzvos." RAV MOSHE FEINSTEIN zt'l (IGROS MOSHE YD 1:80) also writes that a borrower may not say "thank you" to the lender.

(b) RAV SHLOMO ZALMAN AUERBACH zt'l in MINCHAS SHLOMO (1:27) writes the although many have the custom to act in this manner, the Halachah seems to be the opposite. He says that a borrower is permitted to say "thank you," but he may not say "Tizkeh l'Mitzvos." Rav Shlomo Zalman explains that "Tizkeh l'Mitzvos" is a genuine blessing, and thus when the borrower blesses the lender he is giving the lender more than he received. In contrast, when the borrower says "thank you" he does not give a blessing to the lender; rather, he merely shows that he is not an ungrateful boor.

The SEFER MISHPAT HA'RIBIS (1:34) argues that one is permitted to say "Yeyasher Kochacha" ("Yasher Ko'ach"), although he adds that Rav Shlomo Zalman Auerbach himself said later that this also is forbidden. He quotes this opinion in the name of RAV YOSEF SHALOM ELYASHEV shlit'a and RAV MOSHER STERNBUCH shlit'a. The Sefer Mishpat ha'Ribis suggests that the Shulchan Aruch ha'Rav only prohibited giving extra blessings, but not acting in a courteous manner of expressing gratitude. Rav Shlomo Zalman Auerbach apparently understands that since the expression of gratitude may be fulfilled by saying "thank you," giving a blessing comprises an extra expression of gratitude to the lender which is forbidden.

The Bris Yehudah points out another common situation which may involve Ribis. Often, the author of a Sefer borrows money in order to publish his Sefer and he includes a dedication in the his Sefer in honor of the lender. This seems to pose a problem of Ribis. There are various opinions on the matter (see Bris Yehudah ibid.). Rav Moshe Feinstein zt'l (Igros Moshe YD 1:80) writes that if the author of the Sefer writes merely that the lender will be blessed from Heaven because he lent money to publish the Sefer, this is permitted, since the author himself does not bless the lender but says merely that Hash-m blesses people who do Mitzvos. (Y. Montrose)