Then the LORD told Moses, "Go down and prepare the people for my visit. Purify them today and tomorrow, and have them wash their clothing.
Be sure they are ready on the third day, for I will come down upon Mount Sinai as all the people watch.
Set boundary lines that the people may not pass. Warn them, 'Be careful! Do not go up on the mountain or even touch its boundaries. Those who do will certainly die!
Any people or animals that cross the boundary must be stoned to death or shot with arrows. They must not be touched by human hands.' The people must stay away from the mountain until they hear one long blast from the ram's horn. Then they must gather at the foot of the mountain."
So Moses went down to the people. He purified them for worship and had them wash their clothing.
He told them, "Get ready for an important event two days from now. And until then, abstain from having sexual intercourse."
On the morning of the third day, there was a powerful thunder and lightning storm, and a dense cloud came down upon 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 Mount Sinai was covered with smoke because the LORD had descended on it in the form of fire. The smoke billowed into the sky like smoke from a furnace, and the whole mountain shook with a violent earthquake.
As the horn blast grew louder and louder, Moses spoke, and God thundered his reply for all to hear.
The LORD came down on the top of Mount Sinai and called Moses to the top of the mountain. So Moses climbed the mountain.
Then the LORD told Moses, "Go back down and warn the people not to cross the boundaries. They must not come up here to see the LORD, for those who do will die.
Even the priests who regularly come near to the LORD must purify themselves, or I will destroy them."
"But LORD, the people cannot come up on the mountain!" Moses protested. "You already told them not to. You told me to set boundaries around the mountain and to declare it off limits."