Deuteronomy 23:19; Deuteronomy 23:20

19 "When you lend money or food or anything else to Israelites, do not charge them interest.

20 You may charge interest on what you lend to foreigners, but not on what you lend to Israelites. Obey this rule, and the Lord your God will bless everything you do in the land that you are going to occupy.