Deuteronomy 20:16-20

Laws Concerning War with Canaanite Nations

20:16 As for the cities of these peoples that the Lord your God is going to give you as an inheritance, you must not allow a single living thing to survive. 20:17 Instead you must utterly annihilate them – the Hittites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites – just as the Lord your God has commanded you, 20:18 so that they cannot teach you all the abhorrent ways they worship their gods, causing you to sin against the Lord your God. 20:19 If you besiege a city for a long time while attempting to capture it, you must not chop down its trees, for you may eat fruit from them and should not cut them down. A tree in the field is not human that you should besiege it! 20:20 However, you may chop down any tree you know is not suitable for food, and you may use it to build siege works against the city that is making war with you until that city falls.