Jamieson, Fausset and Brown on Genesis 27:39-40

39-40. Behold, thy dwelling shall be the fatness of the earth--The first part is a promise of temporal prosperity, made in the same terms as Jacob's [Ge 27:28]--the second part refers to the roving life of hunting freebooters, which he and his descendants should lead. Though Esau was not personally subject to his brother, his posterity were tributary to the Israelites, till the reign of Joram when they revolted and established a kingdom of their own (2Ki 8:20; 2Ch 21:8-10).