The Father (not frum) of a Baal Teshuva asked his son for a loan. The son agreed to give his Father the loan on condition that he starts to keep Shabbos. Is this a problem of ribis?
In Sefer Chasidim, the author compares Baal Teshuva's to Tzadikim. I have heard that there is a Gemarah that does the same and was wondering if someone could cite that Gemarah.