“When you draw near to a city to fight against it, offer terms of peace to it. And if its answer to you is peace and it opens to you, then all the people who are found in it shall do forced labor for you and shall serve you. But if it makes no peace with you, but makes war against you, then you shall besiege it; and when the LORD your God gives it into your hand you shall put all its males to the sword, but the women and the little ones, the cattle, and everything else in the city, all its spoil, you shall take as booty for yourseves; and you shall enjoy the spoil of your enemies, which the LORD your God has given you. Thus you shall do to all the cities which are very far from you, which are not cities of the nations here. But in the cities of these peoples that the LORD your God gives you for an inheritance, you shall save nothing that breathes …”

Deuteronomy 20:10-16