Exodus 19:20

18All of Mount Sinai smoked, because the LORD descended on it in fire; and its smoke ascended like the smoke of a furnace, and the whole mountain quaked greatly.

19When the sound of the trumpet grew louder and louder, Moses spoke, and God answered him by a voice.

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

21The LORD said to Moses, “Go down, warn the people, lest they break through to the LORD to gaze, and many of them perish.

22Let the priests also, who come near to the LORD, sanctify themselves, lest the LORD break out on them.”