Exodus 34:27-29

27The Lord said to Moses, “Write down these words, for in accordance with these words I have made a covenant with you and with Israel.”

28So he was there with the Lord forty days and forty nights; he did not eat bread, and he did not drink water. He wrote on the tablets the words of the covenant, the ten commandments.

29Now when Moses came down from Mount Sinai with the two tablets of the testimony in his hand – when he came down from the mountain, Moses did not know that the skin of his face shone while he talked with him.