Exodus 34:27-29

Then the LORD said to Moses, “Write down these words, because with these words I have made an agreement with you and Israel.” Moses stayed there with the LORD forty days and forty nights, and during that time he did not eat food or drink water. And Moses wrote the words of the Agreement—the Ten Commandments—on the stone tablets. Then Moses came down from Mount Sinai, carrying the two stone tablets of the Agreement in his hands. But he did not know that his face was shining because he had talked with the LORD.