Exodus 34:27-29 New Revised Standard Version, Anglicised (NRSVA)
27 The Lord said to Moses: Write these words; in accordance with these words I have made a covenant with you and with Israel. 28 He was there with the Lord for 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.[a]
The Shining Face of Moses
29 Moses came down from Mount Sinai. As he came down from the mountain with the two tablets of the covenant[b] in his hand, Moses did not know that the skin of his face shone because he had been talking with God.