Exodus 19:16-25 NASB1995
So it came about on the third day, when it was morning, that there were thunder and lightning flashes and a thick cloud upon the mountain and a very loud trumpet sound, so that all the people who were in the camp trembled. And Moses brought the people out of the camp to meet God, and they stood at the foot of the mountain.
Now Mount Sinai was all in smoke because the LORD descended upon it in fire; and its smoke ascended like the smoke of a furnace, and the whole mountain quaked violently. When the sound of the trumpet grew louder and louder, Moses spoke and God answered him with thunder. The LORD came down on Mount Sinai, to the top of the mountain; and the LORD called Moses to the top of the mountain, and Moses went up. Then the LORD spoke to Moses, “Go down, warn the people, so that they do not break through to the LORD to gaze, and many of them perish. Also let the priests who come near to the LORD consecrate themselves, or else the LORD will break out against them.” Moses said to the LORD, “The people cannot come up to Mount Sinai, for You warned us, saying, ‘Set bounds about the mountain and consecrate it.’ ” Then the LORD said to him, “Go down and come up again, you and Aaron with you; but do not let the priests and the people break through to come up to the LORD, or He will break forth upon them.” So Moses went down to the people and told them.
NASB1995: New American Standard Bible - NASB 1995