Then the told Moses, “Go down and prepare the people for my arrival. Consecrate them today and tomorrow, and have them wash their clothing.
Be sure they are ready on the third day, for on that day the will come down on Mount Sinai as all the people watch.
Mark off a boundary all around the mountain. Warn the people, ‘Be careful! Do not go up on the mountain or even touch its boundaries. Anyone who touches the mountain will certainly be put to death.
No hand may touch the person or animal that crosses the boundary; instead, stone them or shoot them with arrows. They must be put to death.’ However, when the ram’s horn sounds a long blast, then the people may go up on the mountain. ”
References for Exodus 19:13
So Moses went down to the people. He consecrated them for worship, and they washed their clothes.
He told them, “Get ready for the third day, and until then abstain from having sexual intercourse.”
On the morning of the third day, thunder roared and lightning flashed, and a dense cloud came down on the mountain. There was a long, loud blast from a ram’s horn, and all the people trembled.
Moses led them out from the camp to meet with God, and they stood at the foot of the mountain.
All of Mount Sinai was covered with smoke because the had descended on it in the form of fire. The smoke billowed into the sky like smoke from a brick kiln, and the whole mountain shook violently.
As the blast of the ram’s horn grew louder and louder, Moses spoke, and God thundered his reply.
The came down on the top of Mount Sinai and called Moses to the top of the mountain. So Moses climbed the mountain.
Then the told Moses, “Go back down and warn the people not to break through the boundaries to see the , or they will die.
Even the priests who regularly come near to the must purify themselves so that the does not break out and destroy them.”
“But ,” Moses protested, “the people cannot come up to Mount Sinai. You already warned us. You told me, ‘Mark off a boundary all around the mountain to set it apart as holy.’”