Deuteronomy 13:5-9

5Adonai your God you will follow and Him you will fear. His mitzvot you will keep, to His voice you will listen, Him you will serve and to Him you will cling.

6That prophet or dreamer of dreams must be put to death! For he has spoken falsehood against Adonai your God, who brought you out from the land of Egypt and redeemed you from the house of slavery, to entice you from the way Adonai your God commanded you to walk. So you will purge the evil from your midst.

7“Suppose your brother—your mother’s son—or your son or daughter, or the wife of your bosom, or your best friend of your own soul misleads you secretly, saying, ‘Let’s go and serve other gods’—that you and your fathers have not known,

8from among the gods of the peoples around you, near you or far off from you, from one end of the earth to the other.

9You are not to give in or listen to him, your eye is not to pity him, and you are not to spare or conceal him.