Exodus 19:12

19:12 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:

Exodus 19:21

19:21 And the LORD said unto Moses, Go down, charge the people, lest they break through unto the LORD to gaze, and many of them perish.

Leviticus 10:3

10:3 Then Moses said unto Aaron, This [is it] that the LORD spake, saying, I will be sanctified in them that come nigh me, and before all the people I will be glorified. And Aaron held his peace.

Hebrews 12:20

12:20 (For they could not endure that which was commanded, And if so much as a beast touch the mountain, it shall be stoned, or thrust through with a dart: