Exodus 19:23

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

Exodus 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; whoever touches the mount shall surely die:

Joshua 3:4-5

Yet there shall be a space between you and it, about two thousand cubits by measure; do not come near unto it that ye may know the way by which ye must go; for ye 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 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; whoever touches the mount shall surely die:
Joshua 3:4
Yet there shall be a space between you and it, about two thousand cubits by measure; do not come near unto it that ye may know the way by which ye must go; for ye have not passed this way before now.