daf bit: Bava Metzia 75

[cellio]

The torah forbids usury, or lending at interest. Rav Yehudah said in the name of Shmuel: scholars may borrow from each other on interest, because, fully knowing that usery is forbidden, they merely present gifts to each other. Rav Yehudah said in Rav's name that one may lend to his sons and household on interest in order to teach them the bitterness of usury, but the sages disagree because it also teaches the happiness of being a lender in that situation. (75a)

Comments

[chaos-wrangler.livejournal.com]

In some times and places money lending was one of the few occupations Jews were allowed. Add the fact that they might be more likely to have portable money (due to having been expelled from somewhere else with only what they could carry) than the more settled locals, and Christians not wanting to lend money at no interest to each other...