Quran 7:143 — The Purgatory (Al-A'araf)

When Moses came at our appointed time, and his Lord spoke with him, he said, "My Lord, let me look and see You." He said, "You cannot see Me. Look at that mountain; if it stays in its place, then you can see Me." Then, his Lord manifested Himself to the mountain, and this caused it to crumble. Moses fell unconscious. When he came to, he said, "Be You glorified. I repent to You, and I am the most convinced believer."

[7:142] We summoned Moses for thirty* nights, and completed them by adding ten.* Thus, the audience with his Lord lasted forty* nights. Moses said to his brother Aaron, "Stay here with my people, maintain righteousness, and do not follow the ways of the corruptors."

[7:144] He said, "O Moses, I have chosen you, out of all the people, with My messages and by speaking to you. Therefore, take what I have given you and be appreciative."