"There shall not be found among you... a diviner of times"Deuteronomy 18:10.

It is forbidden to predict the auspiciousness of times or dates based on astrological formations: "This day is auspicious, and this day not so." It is also forbidden to act based on such predictions.

Also included in this prohibition is sleight of hand. It is forbidden to deceptively use sleight of hand to convince others that one has magical powers.