Exodus 19:21-23

21and the LORD said to him, “Go down and warn the people so they do not force their way through to see the LORD and many of them perish.

22Even the priests, who approach the LORD, must consecrate themselves, or the LORD will break out against them.”

23Moses said to the LORD, “The people cannot come up Mount Sinai, because you yourself warned us, ‘Put limits around the mountain and set it apart as holy.’ ”