Exodus 34:33-35

33And Moses ended speaking with them; and he had put on his face a veil. 34And when Moses went in before Jehovah to speak with him, he took the veil off, until he came out; and he came out, and spoke to the children of Israel what he was commanded. 35And the children of Israel saw the face of Moses, that the skin of Moses' face shone; and Moses put the veil on his face again, until he went in to speak with him.