Deuteronomy 20:13-18

13When the Lord your God hands the city over to you, kill every man in that city with your swords.

14But take the women and children, the cattle and everything else in the city, including all its goods, as your loot. You may enjoy your enemies’ goods that the Lord your God has given you.

15This is what you must do to all the cities that are far away which don’t belong to the nations nearby.

16However, you must not spare anyone’s life in the cities of these nations that the Lord your God is giving you as your property.

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

18Otherwise, they will teach you to do all the disgusting things they do for their gods, and you will sin against the Lord your God.