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, thou shalt save alive nothing that breatheth:

¹⁷But thou shalt utterly destroy them; namely, the Hittites, and the Amorites, the Canaanites, and the Perizzites, the Hivites, and the Jebusites; as the LORD thy God hath commanded thee:

¹⁸That they teach you not to do after all their abominations, which they have done unto their gods; so should ye sin against the LORD your God.

¹⁹When thou shalt besiege a city a long time, in making war against it to take it, thou shalt not destroy the trees thereof by forcing an axe against them: for thou mayest eat of them, and thou shalt not cut them down (for the tree of the field is man’s life) to employ them in the siege: