Isaiah 8:19-20

19When the people [instead of trusting God] say to you, “Consult the mediums [who try to talk to the dead] and the soothsayers who chirp and whisper and mutter,” should not a people consult their God? Should they consult the dead on behalf of the living?

20[Direct those people] to the law and to the testimony! If their teachings are not in accord with this word, it is because they have no dawn.