Charles Ellicott Commentary Deuteronomy 2:5

"contend not with them; for I will not give you of their land, no, not so much as for the sole of the foot to tread on; because I have given mount Seir unto Esau for a possession." — Deuteronomy 2:5 (ASV)

I have given mount Seir unto Esau —It is worthy of notice that the development of Ishmael preceded that of Isaac, and the inheritance of Esau was won earlier than that of Jacob. (Compare Genesis 25:16 with Genesis 35:23-26, and Genesis 36:31 with Genesis 37:1.) Isaac and Israel were still strangers and sojourners, while the Ishmaelites were princes, with towns and castles, and the Edomites dukes and kings.