Deuteronomy 13:5-9

5The false prophets or visionaries who try to lead you astray must be put to death, for they encourage rebellion against the Lord your God, who redeemed you from slavery and brought you out of the land of Egypt. Since they try to lead you astray from the way the Lord your God commanded you to live, you must put them to death. In this way you will purge the evil from among you.

6“Suppose someone secretly entices you—even your brother, your son or daughter, your beloved wife, or your closest friend—and says, ‘Let us go worship other gods’—gods that neither you nor your ancestors have known.

7They might suggest that you worship the gods of peoples who live nearby or who come from the ends of the earth.

8But do not give in or listen. Have no pity, and do not spare or protect them.

9You must put them to death! Strike the first blow yourself, and then all the people must join in.