Prayer Proximity Excerpted and adapted from a shiur by Dayan Yehoshua Grunwald November 26, 2020…
Favors for the lender
Regarding favors in ribbis, the following levels of friendship and favors are discussed in halachah:
Acquaintances: Favors one would not have done otherwise: A private favor the borrower would not have done previously for the lender, may not be extended to the lender during the loan period (i.e., using the lender’s alarm clock without permission) even with the lender’s knowledge.
Friends: Favors they would have done: The borrower may extend or benefit the lender with private favors he would have done regardless of the loan, even though he may have never done so yet. Such favors require the borrower’s knowledge, and cannot be offered in public.
Close friends: In this case, certain poskim allow even public favors if the favors had been extended previously (it does not suffice to assume he would have done them) and are not perceived as loan related. One must ascertain that the favor is identical to the one extended previously. If he had always extended the favor even without knowledge (allowing to use the alarm clock when not asked permission) then it would be permitted after as well. If the borrower only extended favors with knowledge, he may not do so now without knowledge.
Therefore, one would be allowed to buy a present only if he would have done so regardless of the loan. Otherwise, it is considered ribbis. This would be forbidden even after paying up the loan (ribbis meucheres; see overview for ways to avoid this).
Rav Moshe Feinstein z”l writes that becoming friends through a loan qualifies as friendship, and favors may be extended within the aforementioned parameters.
If a teacher lent a student money for a taxi, the student may chip in for a chanukah present for the teacher. It is logical to assume that the student would have chipped in for the present regardless of the loan, and it would be permitted. It is probable that it would not have the issue of being a public favor either, if done among a group of friends.
When the student is asked to give an exceedingly large amount of money for the present, or if they usually do not chip in for such presents, it would be prohibited.
It is important to note that the above discussion applies only to favors; however, common courtesies, such as holding a door open for someone, are permitted, regardless of their level of friendship. Treating a lender with disrespect is a lack of hakaras hatov.