Exodus 19:14-25

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 LORD 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 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 break through the boundaries to see the LORD, or they will die. Even the priests who regularly come near to the LORD must purify themselves so that the LORD does not break out and destroy them.” “But LORD,” 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.’” But the LORD said, “Go down and bring Aaron back up with you. In the meantime, do not let the priests or the people break through to approach the LORD, or he will break out and destroy them.” So Moses went down to the people and told them what the LORD had said.