Exodus 19:9-20

9And Yhwh said unto Moses, Lo, I come unto thee in a thick cloud, that the people may hear when I speak with thee, and believe thee for ever. And Moses told the words of the people unto Yhwh.

10And Yhwh said unto Moses, Go unto the people, and sanctify them to day and to morrow, and let them wash their clothes, 11And be ready against the third day: for the third day Yhwh will come down in the sight of all the people upon mount Sinai. 12And thou shalt set bounds unto the people round about, saying, Take heed to yourselves, that ye go not up into the mount, or touch the border of it: whosoever toucheth the mount shall be surely put to death: 13There shall not an hand touch it, but he shall surely be stoned, or shot through; whether it be beast or man, it shall not live: when the trumpet soundeth long, they shall come up to the mount.1

14And Moses went down from the mount unto the people, and sanctified the people; and they washed their clothes. 15And he said unto the people, Be ready against the third day: come not at your wives.

16And it came to pass on the third day in the morning, that there were thunders and lightnings, and a thick cloud upon the mount, and the voice of the trumpet exceeding loud; so that all the people that was in the camp trembled. 17And Moses brought forth the people out of the camp to meet with God; and they stood at the nether part of the mount. 18And mount Sinai was altogether on a smoke, because Yhwh descended upon it in fire: and the smoke thereof ascended as the smoke of a furnace, and the whole mount quaked greatly. 19And when the voice of the trumpet sounded long, and waxed louder and louder, Moses spake, and God answered him by a voice. 20And Yhwh came down upon mount Sinai, on the top of the mount: And Yhwh called Moses up to the top of the mount; and Moses went up.