"You shall not destroy the corners of your beard"Leviticus 19:27.

It is forbidden for a man to shave with a razor (or razor-like implement) the "corners" of his beard. The Sages identified five corners: the upper right cheek, the lower right cheek, the upper left cheek, the lower left cheek, and the chin. Shaving the beards with razors was the way of ancient pagan priests.