Exodus 19:16-20

16In the morning of the third day, there was thundering and lightning, a thick cloud on the mountain, and the blast of an exceedingly loud shofar. All the people in the camp trembled.

17Then Moses brought the people out of the camp to meet God, and they stood at the lowest part of the mountain.

18Now the entire Mount Sinai was in smoke, because Adonai had descended upon it in fire. The smoke ascended like the smoke of a furnace. The whole mountain quaked greatly.

19When the sound of the shofar grew louder and louder, Moses spoke, and God answered him with a thunderous sound.

20Then Adonai came down onto Mount Sinai, to the top of the mountain. Adonai called Moses to the top of the mountain, so Moses went up.