Exodus 19:18-21

18Now Mount Sinai was wrapped in smoke because the Lord had descended on it in fire. The smoke of it went up like the smoke of a kiln, and the whole mountain trembled greatly.

19And as the sound of the trumpet grew louder and louder, Moses spoke, and God answered him in thunder.

20The Lord came down on Mount Sinai, to the top of the mountain. And the Lord called Moses to the top of the mountain, and Moses went up.

21And the Lord said to Moses, "Go down and warn the people, lest they break through to the Lord to look and many of them perish.