Deuteronomy 20:16-17

16But of the cities of these peoples, that Jehovah thy God giveth thee for an inheritance, thou shalt save alive nothing that breatheth; 17but thou shalt utterly destroy them: the Hittite, and the Amorite, the Canaanite, and the Perizzite, the Hivite, and the Jebusite; as Jehovah thy God hath commanded thee;