Deuteronomy 20:17

14 But the women, and the little ones, and the cattle, and all that is in the city, [even] all the spoil thereof, shalt thou take unto thyself; and thou shalt eat the spoil of thine enemies, which the LORD thy God hath given thee.

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

16 But of the cities of these people, which the LORD thy God doth give thee [for] an inheritance, thou shalt save alive nothing that breatheth:

17 But 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:

18 That 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.

19 When 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:

20 Only the trees which thou knowest that they [be] not trees for meat, thou shalt destroy and cut them down; and thou shalt build bulwarks against the city that maketh war with thee, until it be subdued.