The people of Israel left Rephidim, and on the first day of the third month after they had left Egypt they came to the desert of Sinai. There they set up camp at the foot of Mount Sinai,
The LORD said to Moses, "I will come to you in a thick cloud, so that the people will hear me speaking with you and will believe you from now on." Moses told the LORD what the people had answered,
Mark a boundary around the mountain that the people must not cross, and tell them not to go up the mountain or even get near it. If any of you set foot on it, you are to be put to death;
you must either be stoned or shot with arrows, without anyone touching you. This applies to both people and animals; they must be put to death. But when the trumpet is blown, then the people are to go up to the mountain."
On the morning of the third day there was thunder and lightning, a thick cloud appeared on the mountain, and a very loud trumpet blast was heard. All the people in the camp trembled with fear.
All of Mount Sinai was covered with smoke, because the LORD had come down on it in fire. The smoke went up like the smoke of a furnace, and all the people trembled violently.
The LORD replied, "Go down and bring Aaron back with you. But the priests and the people must not cross the boundary to come up to me, or I will punish them."