23 And Moses said to God, The people will not be able to approach to the mount of Sina, for thou hast solemnly charged us, saying, Set bounds to the mountain and sanctify it.
Exodus 19:23 Cross References - Brenton
Exodus 19:12
12 And thou shalt separate the people round about, saying, Take heed to yourselves that ye go not up into the mountain, nor touch any part of it: every one that touches the mountain shall surely die.
Joshua 3:4-5
4 But let there be a distance between you and it; ye shall stand as much as two thousand cubits from it. Do not draw nigh to it, that ye may know the way which ye are to go; for ye have not gone the way before.
5 And Joshua said to the people, Sanctify yourselves against to-morrow, for to-morrow the Lord will do wonders among you.