Deuteronomy 13:1-3

IF A prophet arises among you, or a dreamer of dreams, and gives you a sign or a wonder, And the sign or the wonder he foretells to you comes to pass, and if he says, Let us go after other gods–gods you have not known–and let us serve them, You shall not listen to the words of that prophet or to that dreamer of dreams. For the Lord your God is testing you to know whether you love the Lord your God with all your [mind and] heart and with your entire being.