Dear Dairy Excerpted and adapted from a shiur by Rav Yosef Jacobovits May 13, 2021…
HONORING A PHILANTHROPIC LENDER
May a mechaber (author) honor someone who lent money toward the printing costs of their book, or a yeshivah honor a lender by placing an ad thanking them for their kindness?
Does it make a difference if they do so during the life of the loan or afterward?
Rav Moshe Feinstein z”l ruled that one may not place such an ad in a sefer or journal, as it constitutes ribbis devarim.
This only applies if the words indicate a clear expression of gratitude to the lender. However, one may word the ad to simply read “The lender will be blessed by Hashem,” as this is merely stating the true fact that Hashem blesses those who lend money to the needy, but is not an expression of gratitude.
Some permit thanking the lender if the lender was also involved in the editing or other aspect of the printing as well, since the ad will not clearly be in honor of the loan.
After the loan has been repaid, it would be permitted to place a regular ad thanking the lender.