Deuteronomy 13:2; Deuteronomy 13:3

2 and the sign or wonder that he tells you comes to pass, and if he says, 'Let us go after other gods,' which you have not known, 'and let us serve them,'

3 you shall not listen to the words of that prophet or that dreamer of dreams. For the LORD your God is testing you, to know whether you love the LORD your God with all your heart and with all your soul.