Exodus 19:17-20

And Moses brought the people out of the camp to meet God, and they stood at the foot of the mountain. ORD Now Mount Sinai was all in smoke because the LORD descended upon it in fire; and its smoke ascended like the smoke of a furnace, and the whole mountain quaked violently. When the sound of the trumpet grew louder and louder, Moses spoke and God answered him with thunder. The 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.