Deuteronomy 20:13-16

13When the Lord your God hands it over to you, strike down all its males with the sword.

14But you may take the women, dependents, animals, and whatever else is in the city — all its spoil — as plunder. You may enjoy the spoil of your enemies that the Lord your God has given you.

15This is how you are to treat all the cities that are far away from you and are not among the cities of these nations.

16However, you must not let any living thing survive among the cities of these people the Lord your God is giving you as an inheritance.