Deuteronomy 13:5-9

5But that prophet or that dreamer of dreams shall be put to death, because he has taught rebellion against the Lord your God, who brought you out of the land of Egypt and redeemed you out of the house of slavery, to make you leave the way in which the Lord your God commanded you to walk. So you shall purge the evil from your midst.

6"If your brother, the son of your mother, or your son or your daughter or the wife you embrace or your friend who is as your own soul entices you secretly, saying, 'Let us go and serve other gods,' which neither you nor your fathers have known,

7some of the gods of the peoples who are around you, whether near you or far off from you, from the one end of the earth to the other,

8you shall not yield to him or listen to him, nor shall your eye pity him, nor shall you spare him, nor shall you conceal him.

9But you shall kill him. Your hand shall be first against him to put him to death, and afterward the hand of all the people.