Exodus 19:12 in the King James Version
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:
Context
11 and be ready for the third day; for on the third day the LORD will come down in the sight of all the people on Mount Sinai.
12 You shall set bounds to the people all around, saying, ‘Be careful that you don’t go up onto the mountain, or touch its border. Whoever touches the mountain shall be surely put to death.
13 No hand shall touch him, but he shall surely be stoned or shot through; whether it is animal or man, he shall not live.’ When the trumpet sounds long, they shall come up to the mountain.”