Deuteronomy 20:9-11

Amplified Bible

⁹ And it shall be when the officers have finished speaking to the soldiers, they shall appoint commanders of armies over them.

¹⁰ “When you advance to a city to fight against it, you shall [first] offer it terms of peace. ¹¹ If that city accepts your terms of peace and opens its gates to you, then all the people who are found in it shall become your forced labor and shall serve you.