Exodus 19:13

10 Yahweh said to Moses, "Go to the people, and sanctify them today and tomorrow, and let them wash their garments,

11 and be ready against the third day; for on the third day Yahweh will come down in the sight of all the people on Mount Sinai.

12 You shall set bounds to the people round about, saying, `Be careful that you don`t go up onto the mountain, or touch its border. Whoever touches the mountain shall be surely put to death.

13 No hand shall touch him, but he shall surely be stoned or shot through; whether it is animal or man, he shall not live.` When the trumpet sounds long, they shall come up to the mountain."

14 Moses went down from the mountain to the people, and sanctified the people; and they washed their clothes.

15 He said to the people, "Be ready by the third day. Don`t have sexual relations with a woman."

16 It happened on the third day, when it was morning, that there were thunders and lightnings, and a thick cloud on the mountain, and the sound of an exceedingly loud trumpet; and all the people who were in the camp trembled.