Rashi on Leviticus 19:31/רש"י על ויקרא י״ט:ל״א

1אל תפנו DO NOT TURN [TO THE אבת NOR TO THE ידענים] — This is a warning addressed to the necromancers and the charmers themselves (not to the people who consult these tricksters). The בעל אוב, the controller of the spirit אוב, as the necromancer is called (cf. I Samuel 28:7), is identical with the פיתום (in Greek: πύξωυ); he is one who speaks out of his arm-pit; ידעני is one who puts a bone of an animal the name of which is ידוע into his mouth and the bone speaks (Sanhedrin 65b).

2אל תבקשו means DO NOT SEEK to busy yourselves with them, for if you busy yourselves with them, you will become defiled in My sight and I shall abhor you.

3אני ה' אלהיכם I AM THE LORD YOUR GOD — Just think Whom you are changing (by these practices which lead to idolatry) for whom! (Sifra, Kedoshim, Chapter 7 11)