Deuteronomy 13

2 and the sign or the wonder comes to pass, of which he spoke to you, saying, "Let’s go after other gods" (which you have not known) "and let’s serve them," 3 you shall not listen to the words of that prophet, or to that dreamer of dreams; for Yahweh your God is testing you, to know whether you love Yahweh your God with all your heart and with all your soul.