Exodus 19:11-15

and have them ready for the third day, for on the third day the Lord will come down on Mount Sinai in the sight of all the people.

But you shall set boundaries for the people all around, saying, ‘Beware that you do not go up on the mountain or touch the border of it; whoever touches the mountain shall certainly be put to death.

No hand shall touch him, but he shall certainly be stoned or shot through; whether animal or person, the violator shall not live.’ When the ram’s horn 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.

He also said to the people, “Be ready for the third day; do not go near a woman.”