Halakha Ulangan 20:16: Ben Ish Hai, Mishneh Torah, Kings and Wars, Mishneh Torah, Negative Mitzvot & Sefer Chasidim

"And you shall not fear the people of the land, for they are our bread; their protection has departed from them, and God is with us; do not fear them" (Numbers 14:9), it seems to me, with God's help, that it is known that the nations of the world have their strength from the sparks of holiness that are mixed in their "shell", for the sparks of holiness are their life and power. And therefore God commanded to kill off the Canaanites, as it is written "You shall surely destroy them etc." (Deuteronomy 12:2) and "You shall not let any soul live" (Deuteronomy 20:16), because there were many and mighty sparks of holiness in their shell, and if Israel had treated them well and kept them in the world, they would not have been able to separate those sparks of holiness, and on the contrary, the "shell" would have been strengthened more, but by Israel destroying them below and killing them off to fulfill the commandment of the Lord, they were able to crush and destroy also the "shell" and take out what was "swallowed from its mouth".

It is a Positive Commandment to exterminate the Seven Nations, as it says, “surely, you shall destroy them” (Deut. 20:17). Anyone who comes across any of these nations and fails to kill them violates a Negative Commandment, as it says, “you shall not keep alive any soul” (Deut. 20:16). Nonetheless, they have already all been destroyed and their memory forgotten.

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.