Deuteronomy 13:1-5

If a prophet or dreamer of dreams arises among you and proclaims a sign or wonder to you, and if the sign or wonder he has spoken to you comes about, but he says, “Let us follow other gods (which you have not known) and let us worship them,” you must not listen to the words of that prophet or dreamer. For the LORD your God is testing you to find out whether you love Him with all your heart and with all your soul. You are to follow the LORD your God and fear Him. Keep His commandments and listen to His voice; serve Him and hold fast to Him. Such a prophet or dreamer must be put to death, because he has advocated rebellion against the LORD your God, who brought you out of the land of Egypt and redeemed you from the house of slavery; he has tried to turn you from the way in which the LORD your God has commanded you to walk. So you must purge the evil from among you.