Exodus 34:28-35

So he was there with the LORD forty days and forty nights; he neither ate bread nor drank water. And He wrote on the tablets the words of the covenant, the Ten Commandments. Now it was so, when Moses came down from Mount Sinai (and the two tablets of the Testimony were in Moses’ hand when he came down from the mountain), that Moses did not know that the skin of his face shone while he talked with Him. So when Aaron and all the children of Israel saw Moses, behold, the skin of his face shone, and they were afraid to come near him. Then Moses called to them, and Aaron and all the rulers of the congregation returned to him; and Moses talked with them. Afterward all the children of Israel came near, and he gave them as commandments all that the LORD had spoken with him on Mount Sinai. And when Moses had finished speaking with them, he put a veil on his face. But whenever Moses went in before the LORD to speak with Him, he would take the veil off until he came out; and he would come out and speak to the children of Israel whatever he had been commanded. And whenever the children of Israel saw the face of Moses, that the skin of Moses’ face shone, then Moses would put the veil on his face again, until he went in to speak with Him.