Deuteronomy 13:12-15

12Suppose you should hear in one of your cities, which the Lord your God is giving you as a place to live, that

13some evil people have departed from among you to entice the inhabitants of their cities, saying, “Let’s go and serve other gods” (whom you have not known before).

14You must investigate thoroughly and inquire carefully. If it is indeed true that such a disgraceful thing is being done among you,

15you must by all means slaughter the inhabitants of that city with the sword; annihilate with the sword everyone in it, as well as the livestock.