Exodus 19:16

16 And it came to pass on the third day when the morning came, that there were thunders and lightnings and a thick cloud upon the mount and the voice of the shofar {ram’s horn} exceeding loud, so that all the people that were in the camp trembled.

Exodus 19:16 In-Context

14 And Moses went down from the mount unto the people and sanctified the people, and they washed their clothes.
15 And he said unto the people, Be ready against the third day; come not at your women.
16 And it came to pass on the third day when the morning came, that there were thunders and lightnings and a thick cloud upon the mount and the voice of the shofar {ram’s horn} exceeding loud, so that all the people that were in the camp trembled.
17 And Moses brought forth the people out of the camp to meet with God, and they stood at the lower part of the mount.
18 And all Mount Sinai smoked because the LORD had descended upon it in fire, and its smoke ascended as the smoke of a furnace, and the whole mount quaked greatly.
The Jubilee Bible (from the Scriptures of the Reformation), edited by Russell M. Stendal, Copyright © 2000, 2001, 2010