Deuteronomy 13:15-17

you must kill with a sword everyone who lives in that city. Destroy the city completely and kill everyone in it, as well as the animals, with a sword. Gather up everything those people owned, and put it in the middle of the city square. Then completely burn the city and everything they owned as a burnt offering to the LORD your God. That city should never be rebuilt; let it be ruined forever. Don’t keep for yourselves any of the things found in that city, so the LORD will not be angry anymore. He will give you mercy and feel sorry for you, and he will make your nation grow larger, as he promised to your ancestors.