Charles Ellicott Commentary Numbers 20:27

"And Moses did as Jehovah commanded: and they went up into mount Hor in the sight of all the congregation." — Numbers 20:27 (ASV)

And they went up into Mount Hor ... Some would render to the summit of the mountain, and regard these words as equivalent to those which occur in the following verse, the top of the mount; but the same words occur in the fourth verse of the following chapter, where they cannot be thus understood.

In the sight of all the congregation. The place where the people encamped is called Moseroth in Numbers 33:30, and Mosera in Deuteronomy 10:6.