Deuteronomy 23:19-20

Thou shalt not lend upon usury to thy brother; usury of money, usury of victuals, usury of any thing that is lent upon usury:

Thou shalt not lend upon usury to thy brother ... unto a stranger. The Israelites, being employed chiefly in the culture of the soil and the rearing of cattle, would have little occasion to borrow except for personal use through temporary want and poverty. They lived in a simple state of society, and hence, they were encouraged to lend to each other in a friendly way, without any hope of gain. But the case was different with foreigners, who engaged in trade and commerce-borrowed to enlarge their capital, and might reasonably be expected to pay interest on their loans, the more especially as the risk of lending them was greater, and the bond of consanguinity did not exist. Besides, the distinction was admirably conducive to keeping the Israelites separate from the rest of the world.