Exodus:19:16-18-20
rsv@Exodus:19:16 @ On the morning of the third day there were thunders and lightnings, and a thick cloud upon the mountain, and a very loud trumpet blast, so that all the people who were in the camp trembled.
rsv@Exodus:19:17 @ Then Moses brought the people out of the camp to meet God; and they took their stand at the foot of the mountain.
rsv@Exodus:19:18 @ And Mount Sinai was wrapped in smoke, because the LORD descended upon it in fire; and the smoke of it went up like the smoke of a kiln, and the whole mountain quaked greatly.