John Gill Commentary Deuteronomy 2:4

"And command thou the people, saying, Ye are to pass through the border of your brethren the children of Esau, that dwell in Seir; and they will be afraid of you: take ye good heed unto yourselves therefore;" — Deuteronomy 2:4 (ASV)

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.