Exodus 19:17-20

Then Moses led the people out of the camp to meet with God, and they stood at the foot of the mountain. Mount Sinai was covered with smoke, because the LORD descended on it in fire. The smoke billowed up from it like smoke from a furnace, and the whole mountain trembled violently. As the sound of the trumpet grew louder and louder, Moses spoke and the voice of God answered him. The LORD descended to the top of Mount Sinai and called Moses to the top of the mountain. So Moses went up