Deuteronomy 20:15-19

¹⁵Thus shalt thou do unto all the cities which are very far off from thee, which are not of the cities of these nations.

¹⁶But of the cities of these people, which the Lord thy God doth give thee for an inheritance, shalt thou not let live a single soul.

¹⁷But thou shalt utterly devote them; namely, the Hittites, and the Emorites, the Canaanites, and the Perizzites, and the Hivites, and the Jebusites; as the Lord thy God hath commanded thee;

¹⁸In order that they may not teach you to do in accordance with all their abominations, which they have done unto their gods; and ye would thus sin against the Lord your God.

¹⁹When thou besiegest a city a long time, to make war against it to capture it, thou shalt not destroy the trees thereof by forcing an axe against them; for of them thou mayest eat, and thou shalt not cut them down, for man liveth of the trees of the field, to employ them in thy siege;