הלכה אויף דברים 2:34

If they do not come to peaceful terms or they make peace but do not accept the Seven Commandments, we engage in war against them and slay all their adult males. We take all their money and children as spoils. We do not kill the women or minors, as it says, “the women and the children” (see Deut. 20:14 and 2:34) which means the male children. To what do we refer? To a Discretionary War with one of the other nations. However, with one of the Seven Nations or with Amalek who do not make peace, we leave no soul alive, as it says, “so you shall do with everyone…only of the cities of the nations…do not leave alive any soul” (Deut. 20:15-16), and regarding Amalek it says, “erase the memory of Amalek” (Deut. 25:19). How do we know that this is referring to those who do not make peace with us? For it says, “there was no city which came to peace with the Children of Israel except the Chivites, dwellers of Givon. Everything, they took in the war. For from G-d their hearts were strengthened to the call of war with Israel, so that they may be destroyed.” (Joshua 11:19-20). They were offered peace, and refused.