Exodus 19:23

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

Exodus 19:12

And thou shalt set bounds to the people round about, 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:

Joshua 3:4-5

Yet there shall be a space between you and it, about two thousand cubits by measure: come not near to it, that ye may know the way by which ye must go: for ye have not passed this way heretofore.

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 thou shalt set bounds to the people round about, 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:
Joshua 3:4
Yet there shall be a space between you and it, about two thousand cubits by measure: come not near to it, that ye may know the way by which ye must go: for ye have not passed this way heretofore.