Exodus 34
28 Ref He was there with Yahweh forty days and forty nights; he neither ate bread, nor drank water. He wrote on the tablets the words of the covenant, the ten commandments.
29 Ref It happened, when Moses came down from Mount Sinai with the two tablets of the testimony in Moses' hand, when he came down from the mountain, that Moses didn't know that the skin of his face shone by reason of his speaking with him.