Deuteronomy 13:7-9

New Catholic Bible

^7 [a]Even if your brother, the son of your mother, or your son, or your daughter, or your wife, or your closest friend secretly tempts you saying, “Let us go and serve other gods whom neither you nor your forefathers have known,” ⁸ the gods of the people living around us, whether they be near or far, wherever they are upon the whole face of the earth, ⁹ you are not to agree to do this with him or even listen to him. You must show him no pity, you should not spare or conceal him.