Deuteronomy 20:15
King James Version
“Thus shalt thou do unto all the cities very far off from thee, which not of the cities of these nations.”
Context
12And if it will make no peace with thee, but will make war against thee, then thou shalt besiege it:
13And when the LORD thy God hath delivered it into thine hands, thou shalt smite every male thereof with the edge of the sword:
14But the women, and the little ones, and the cattle, and all that is in the city, 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.
15Thus shalt thou do unto all the cities very far off from thee, which not of the cities of these nations.
16But of the cities of these people, which the LORD thy God doth give thee an inheritance, thou shalt save alive nothing that breatheth:
17But thou shalt utterly destroy them; 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.