Exodus 19:14-16

American Standard Version

¹⁴ And Moses went down from the mount unto the people, and sanctified the people; and they washed their garments. ¹⁵ And he said unto the people, Be ready against the third day: come not near a woman.

¹⁶ And it came to pass on the third day, when it was morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of a trumpet exceeding loud; and all the people that were in the camp trembled.