John Gill Commentary Deuteronomy 2

Then we turned
From Kadesh, where they had been many days, and so also their backs on the land of Canaan, on the borders of which they had been:

and took our journey into the wilderness, by the way of the Red sea, as
the Lord spoke to me ;
(Deuteronomy 1:40)

and we compassed Mount Seir many days ;
Many think by Mount Seir is meant the whole mountainous country of Edom, about which they travelled to and fro in the wilderness that lay near it for the space of thirty eight years, which they suppose are meant by many days.

But I rather think they came to this mount towards the close of the thirty eight years, before they came to Kadesh, from where they sent messengers to Edom, which they went round about for several days.

And the Lord spoke to me
While about Mount Seir:

saying ;
as follows.

You have compassed this mountain long enough
It was time to be gone from there, as from Horeb, (Deuteronomy 1:6) ,

turn you northward ;
from the southern border of Edom towards the land of Canaan, which lay north. It was from Eziongeber in the land of Edom, from where the Israelites came to Kadesh, where they sent messengers to the king of Edom, to desire a passage through his land; see (Numbers 33:36) (20:14) .

And command you the people
Give them a strict charge:

saying, you are to pass through the coast of your brethren the children
or Esau :
not through the midst of their country, for that the king of Edom would not admit of, but by or on the border of it:

and they shall be afraid of you ;
lest such a numerous body of people as Israel were should seize upon their country, and dispossess them of it, they having been so long, wanderers in a wilderness near them:

take you good heed to yourselves therefore ;
that they did not take any advantage of their fears, and fall upon them, and do them mischief, or that they did not provoke them to battle and overcome them.

Ver. 5 Meddle not with them
Contend not with them in battle, nor provoke them to it:

for I will not give you of their land, no not so much as a foot breadth ;
or as the sole of a man's foot can tread on, signifying that they should not have the least part of it, not any at all. Jarchi makes mention of an exposition of theirs, that he would give them nothing of it until should come the day of the treading of the sole of the foot in the mount of Olives, (Zechariah 14:4) , meaning not till the days of the Messiah, when Edom should be a possession of Israel; see (Numbers 24:18) , (Obadiah 1:19)

because I have given Mount Seir unto Esau for a possession ;
and therefore not to be taken away from them; they have a right of inheritance of it; see (Genesis 36:8) (Joshua 24:4) .