Musar zu Wajikra 19:31

אל תפנו אל האובות ואל הידעונים . "Do not turn to ghosts and do not inquire of familiar spirits." The reason is that such ghosts are apt to turn you away from having faith in G–d who is the Creator of all. The method employed by people who are experts in communicating with the dead involve manipulating the powers of impurity. When these "dead" spirits make predictions of the future some will come true, others will not. The reason the Torah calls these ghosts אבות, "fathers," is that they are the "patriarchs" of all the forces of impurity. The Torah says "do not turn to them" instead of "do not practice or perform such rites" so that you should not even contemplate having anything to do with such practices. The word תפנו is related to פנים, face. Merely looking at such ghosts introduces impurity into the atmosphere; it is just as damaging as looking at the face of a wicked person.