Charles Ellicott 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)

You are to pass through the coast. —Literally, You are passing through the border. This was apparently said before the permission was asked, and in view of the request made for it (Numbers 20:17). But Edom refused to let Israel pass through his coast or border (Numbers 20:21).

They shall be afraid of you. —According to the prophecy in the song of Moses (Exodus 15:15), Then the dukes of Edom shall be amazed.