Exodus 19:10-13

And Jehovah said unto Moses, Go unto the people, and sanctify them to-day and to-morrow, and let them wash their garments, and be ready against the third day; for the third day Jehovah will come down in the sight of all the people upon mount Sinai. And 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: no hand shall touch him, but he shall surely be stoned, or shot through; whether it be beast or man, he shall not live: when the trumpet soundeth long, they shall come up to the mount.