Deuteronomy 20:15

11It shall be, if it gives you answer of peace and opens to you, then it shall be that all the people who are found therein shall become forced laborers to you, and shall serve you.

12If it will make no peace with you, but will make war against you, then you shall besiege it.

13When the LORD your God delivers it into your hand, you shall strike every male of it with the edge of the sword;

14but the women, the little ones, the livestock, and all that is in the city, even all its plunder, you shall take for plunder for yourself. You may use the plunder of your enemies, which the LORD your God has given you.

15Thus you shall do to all the cities which are very far off from you, which are not of the cities of these nations.

16But of the cities of these peoples that the LORD your God gives you for an inheritance, you shall save alive nothing that breathes;

17but you shall utterly destroy them: the Hittite, the Amorite, the Canaanite, the Perizzite, the Hivite, and the Jebusite, as the LORD your God has commanded you;

18that they not teach you to follow all their abominations, which they have done for their gods; so would you sin against the LORD your God.

19When you shall besiege a city a long time, in making war against it to take it, you shall not destroy its trees by wielding an ax against them; for you may eat of them. You shall not cut them down, for is the tree of the field man, that it should be besieged by you?