Deuteronomy 20:10-20

10“When you approach a city to fight against it, you shall 1offer it terms of peace. 11And if it 2agrees to make peace with you and opens to you, then all the people who are found in it shall become your 3forced labor and serve you. 12However, if it does not make peace with you, but makes war against you, then you shall besiege it. 13When the Lord your God gives it into your hand, 4you shall strike all the 5men in it with the edge of the sword. 14However, the women, the children, 6the animals, and everything that is in the city, all of its spoils, you shall take as plunder for yourself; and you shall 7use the spoils of your enemies which the Lord your God has given you. 15This is what you shall do to all the cities that are very far from you, which are not of the cities of these nations 8nearby. 169Only in the cities of these peoples that the Lord your God is giving you as an inheritance, you shall not leave anything that breathes alive. 17Instead, you shall 10utterly destroy them, the Hittite and the Amorite, the Canaanite and the Perizzite, the Hivite and the Jebusite, just as the Lord your God has commanded you, 18so that they will not teach you to do 1112all the same detestable practices of theirs which they have done for their gods, 13by which you would 14sin against the Lord your God.

19“When you besiege a city for a long time, to make war against it in order to capture it, you shall not destroy its trees by swinging an axe against them; for you may eat from them, so you shall not cut them down. For 15is the tree of the field a human, that it should 16be besieged by you? 20Only the trees that you know 17are not fruit trees you shall destroy and cut down, so that you may construct siegeworks against the city that is making war against you until it falls.