Exodus 19:23

And Moses said to the Lord, The people will not be able to come up the mountain, for you gave us orders to put limits round the mountain, marking it out and making it holy.

Exodus 19:12

And let limits be marked out for the people round the mountain, and say to them, Take care not to go up the mountain or near the sides of it: whoever puts his foot on the mountain will certainly come to his death:

Joshua 3:4-5

But let there be a space between you and it of about two thousand cubits: come no nearer to it, so that you may see the way you have to go, for you have not been over this way before.

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 let limits be marked out for the people round the mountain, and say to them, Take care not to go up the mountain or near the sides of it: whoever puts his foot on the mountain will certainly come to his death:
Joshua 3:4
But let there be a space between you and it of about two thousand cubits: come no nearer to it, so that you may see the way you have to go, for you have not been over this way before.

Basic English, produced by Mr C. K. Ogden of the Orthological Institute - public domain