Deuteronomy 20:10-14

When you approach a city to wage war against it, offer it terms of peace. If it accepts your terms and submits to you, all the people found in it will become your slaves. If it does not accept terms of peace but makes war with you, then you are to lay siege to it. The LORD your God will deliver it over to you and you must kill every single male by the sword. However, the women, little children, cattle, and anything else in the city – all its plunder – you may take for yourselves as spoil. You may take from your enemies the plunder that the LORD your God has given you.