זוהר שמות — דף קצד ע”א

As a consequence of the sin of the golden calf, all the elevated rungs and lights were removed from Israel, and the evil serpent returned as before, bringing death back into the world. When Moses descended from the mountain, his face shone with rays and they were afraid to approach him. These rays were the weapons that had been removed from Israel at the changing of the Tablets. Moses himself was forced to veil his face so the rays would not harm the Israelites — rays linked to the well of the impure side.