Exodus 19:10-13

10And the LORD said to Moses, Go to the people, and sanctify them to day and to morrow, and let them wash their clothes, 11And be ready for the third day: for on the third day the LORD will come down in the sight of all the people upon mount Sinai. 12And thou shalt set bounds to the people all around, saying, Take heed to yourselves, that ye go not up upon the mount, or touch the border of it: whoever 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