Deuteronomy 20:13, 16-18

And when the LORD your God delivers it into your hands, you shall strike every male in it with the edge of the sword.

“But of the cities of these peoples which the LORD your God gives you as an inheritance, you shall let nothing that breathes remain alive, but you shall utterly destroy them: the Hittite and the Amorite and the Canaanite and the Perizzite and the Hivite and the Jebusite, just as the LORD your God has commanded you, lest they teach you to do according to all their abominations which they have done for their gods, and you sin against the LORD your God.