Then it came to pass on the third day, in the morning, that there were thunderings and lightnings, and a thick cloud on the mountain; and the sound of the trumpet was very loud, so that all the people who were in the camp trembled.
Exodus 19:16
Surrounding context
19:15 And he said to the people, "Be ready for the third day; do not come near your wives."
19:16 Then it came to pass on the third day, in the morning, that there were thunderings and lightnings, and a thick cloud on the mountain; and the sound of the trumpet was very loud, so that all the people who were in the camp trembled.
19:17 And Moses brought the people out of the camp to meet with God, and they stood at the foot of the mountain.