Deuteronomy 13:1-3

Suppose a prophet or one who foretells by dreams should appear among you and show you a sign or wonder, and the sign or wonder should come to pass concerning what he said to you, namely, “Let us follow other gods” – gods whom you have not previously known – “and let us serve them.” You must not listen to the words of that prophet or dreamer, for the LORD your God will be testing you to see if you love him with all your mind and being.