Deuteronomy 23:19-20 - Interest On Loans
19 Thou shalt not lend upon usury to thy brother, usury of money, usury of food, usury of any thing that is lent upon usury. 20 Unto a stranger thou may lend upon usury, but unto thy brother thou shalt not lend upon usury that the LORD thy God may bless thee in all the work of thy hands upon the land which thou doest enter in to inherit.