Exodus 19:23

And Moses said to Jehovah, The people cannot come up to Mount Sinai. For You commanded us, saying, Set bounds around the mountain, and sanctify it.

Exodus 19:12

And you shall set bounds to the people round about, saying, Take heed to yourselves. Do not go up into the mountain, or touch the border of it. Whoever touches the mountain shall be surely put to death.

Joshua 3:4-5

Yet keep a space between you and it, about two thousand cubits by measure. Do not come near it, so that you may know the way by which you must go. For you have not passed this way before now.

Treasury of Scripture Knowledge

Summary

And Moses said unto the LORD, The people cannot come up to mount Sinai: for thou chargedst us, saying, Set bounds about the mount, and sanctify it.

Bible References

Set bounds

Exodus 19:12
And you shall set bounds to the people round about, saying, Take heed to yourselves. Do not go up into the mountain, or touch the border of it. Whoever touches the mountain shall be surely put to death.
Joshua 3:4
Yet keep a space between you and it, about two thousand cubits by measure. Do not come near it, so that you may know the way by which you must go. For you have not passed this way before now.