Exodus 19:16

16 On the morning of the third day there was thunder and lightning, as well as a thick cloud on the mountain, and a blast of a trumpet so loud that all the people who were in the camp trembled.

Exodus 19:16 In-Context

14 So Moses went down from the mountain to the people. He consecrated the people, and they washed their clothes.
15 And he said to the people, "Prepare for the third day; do not go near a woman."
16 On the morning of the third day there was thunder and lightning, as well as a thick cloud on the mountain, and a blast of a trumpet so loud that all the people who were in the camp trembled.
17 Moses brought the people out of the camp to meet God. They took their stand at the foot of the mountain.
18 Now Mount Sinai was wrapped in smoke, because the Lord had descended upon it in fire; the smoke went up like the smoke of a kiln, while the whole mountain shook violently.
New Revised Standard Version Bible, copyright 1989, Division of Christian Education of the National Council of the Churches of Christ in the United States of America. Used by permission. All rights reserved.