Deuteronomy 20:10-18

When you come up against a city to attack it, call out, “Peace?” If they answer, “Yes, peace!” and open the city to you, then everyone found there will be conscripted as forced laborers and work for you. But if they don’t settle for peace and insist on war, then go ahead and attack. GOD, your God, will give them to you. Kill all the men with your swords. But don’t kill the women and children and animals. Everything inside the town you can take as plunder for you to use and eat—GOD, your God, gives it to you. This is the way you deal with the distant towns, the towns that don’t belong to the nations at hand. But with the towns of the people that GOD, your God, is giving you as an inheritance, it’s different: don’t leave anyone alive. Consign them to holy destruction: the Hittites, Amorites, Canaanites, Perizzites, Hivites, and Jebusites, obeying the command of GOD, your God. This is so there won’t be any of them left to teach you to practice the abominations that they engage in with their gods and you end up sinning against GOD, your God.