Exodus 19:18

19:18 Now Mount Sinai was completely covered with smoke because the Lord had descended on it in fire, and its smoke went up like the smoke of a great furnace, and the whole mountain shook violently.

Exodus 19:23

19:23 Moses said to the Lord, “The people are not able to come up to Mount Sinai, because you solemnly warned us, ‘Set boundaries for the mountain and set it apart.’”

Exodus 24:16

24:16 The glory of the Lord resided on Mount Sinai, and the cloud covered it for six days. On the seventh day he called to Moses from within the cloud.

Exodus 34:4

34:4 So Moses cut out two tablets of stone like the first; early in the morning he went up to Mount Sinai, just as the Lord had commanded him, and he took in his hand the two tablets of stone.