Exodus 19:12-16

And you shall set limits for the people all around, saying, ‘Take care not to go up into the mountain or touch the edge of it. Whoever touches the mountain shall be put to death. No hand shall touch him, but he shall be stoned or shot; whether beast or man, he shall not live.’ When the trumpet sounds a long blast, they shall come up to the mountain.” So Moses went down from the mountain to the people and consecrated the people; and they washed their garments. And he said to the people, “Be ready for the third day; do not go near a woman.” On the morning of the third day there were thunders and lightnings and a thick cloud on the mountain and a very loud trumpet blast, so that all the people in the camp trembled.