Exodus 34:29-35

When Moses came down from Mount Sinai with the two tablets of the Testimony in his hand, he did not know that the skin of his face was shining [with a unique radiance] because he had been speaking with God. When Aaron and all the Israelites saw Moses, behold, the skin of his face shone, and they were afraid to approach him. But Moses called to them, and Aaron and all the leaders of the congregation returned to him; and he spoke to them. Afterward all the Israelites approached him, and he commanded them to do everything that the LORD had said to him on Mount Sinai. When Moses had finished speaking with them, he put a veil over his face. But whenever Moses went in before the LORD to speak with Him, he would take off the veil until he came out. When he came out and he told the Israelites what he had been commanded [by God], the Israelites would see the face of Moses, how his skin shone [with a unique radiance]. So Moses put the veil on his face again until he went in to speak with God.