Deuteronomy 20:15

13When the LORD your God delivers it into your hand, you shall strike every male of it with the edge of the sword;

14but the women, the little ones, the livestock, and all that is in the city, even all its plunder, you shall take for plunder for yourself. You may use the plunder of your enemies, which the LORD your God has given you.

15Thus you shall do to all the cities which are very far off from you, which are not of the cities of these nations.

16But of the cities of these peoples that the LORD your God gives you for an inheritance, you shall save alive nothing that breathes;

17but you shall utterly destroy them: the Hittite, the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite, as the LORD your God has commanded you;