Exodus 19:12

19:12 You must set boundaries for the people all around, saying, ‘Take heed to yourselves not to go up on the mountain nor touch its edge. Whoever touches the mountain will surely be put to death!

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 24:18

24:18 Moses went into the cloud when he went up the mountain, and Moses was on the mountain forty days and forty nights.

Exodus 34:2

34:2 Be prepared in the morning, and go up in the morning to Mount Sinai, and station yourself for me there on the top of the mountain.