Kiddushin with a Loan Forgiveness: Rashi vs. Rambam on Hanoas Mechilah

The Gemara (גמרא) in Kiddushin discusses whether one can be mekadesh a woman by forgiving (being mechiel) her debt. The central question is whether such "hanoas mechilah" (benefit of forgiveness) constitutes valid kiddushin. Rashi (רש"י)'s approach, as analyzed in depth in this shiur, is that one cannot be mekadesh with the actual debt relief itself. Rather, the kiddushin only works with the pruta (small coin) she would have paid to someone else—or to him—to perform the service of getting him to forgive the debt or to extend the loan period. This is comparable to cases like "rekod lefanai" (dance before me) or "dabar lach lashilton" (speak on your behalf to the authorities), where kiddushin is effected through a service that has measurable value. Rashi emphasizes that merely extending the loan period (harvach zman) is not the same as changing the terms of the loan itself. If the original loan was due in Elul, and he agrees not to collect for three more months but the debt technically remains due in Elul, this does not constitute agranata (interest for delayed payment). It is simply an agreement not to bother her for collection. The loan remains unchanged in its fundamental terms. This has practical halachic ramifications; for instance, if Shemita arrives after the original due date but before the extended period ends, the debt would still be cancelled by Shemita because the actual loan obligation was due before Shemita.