Deuteronomy 20:13-18

13When the Lord your God hands the town over to you, use your swords to kill every man in the town.

14But you may keep for yourselves all the women, children, livestock, and other plunder. You may enjoy the plunder from your enemies that the Lord your God has given you.

15“But these instructions apply only to distant towns, not to the towns of the nations in the land you will enter.

16In those towns that the Lord your God is giving you as a special possession, destroy every living thing.

17You must completely destroy the Hittites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites, just as the Lord your God has commanded you.

18This will prevent the people of the land from teaching you to imitate their detestable customs in the worship of their gods, which would cause you to sin deeply against the Lord your God.