Deuteronomy 23:20 in the World English Bible
You may charge a foreigner interest; but you shall not charge your brother interest, that the LORD your God may bless you in all that you put your hand to, in the land where you go in to possess it.
Context
19 Thou shalt not lend upon usury to thy brother; usury of money, usury of victuals, usury of any thing that is lent upon usury:
20 Unto a stranger thou mayest lend upon usury; but unto thy brother thou shalt not lend upon usury: that the LORD thy God may bless thee in all that thou settest thine hand to in the land whither thou goest to possess it.
21 When thou shalt vow a vow unto the LORD thy God, thou shalt not slack to pay it: for the LORD thy God will surely require it of thee; and it would be sin in thee.