Charles Ellicott Commentary Genesis 27:29

"Let peoples serve thee, And nations bow down to thee. Be lord over thy brethren, And let thy mother`s sons bow down to thee. Cursed be every one that curseth thee, And blessed be every one that blesseth thee." — Genesis 27:29 (ASV)

Let people serve you. —Heb., peoples. Up to this point the blessing had been general, but now Isaac bestows the birthright, carrying with it widespread dominion, precedence over all other members of the family, and special blessedness. The phrases your brethren and your mother’s sons include all nations sprung from Abraham, and all possible offshoots from Isaac’s own descendants.

Cursed ... and blessed. —This is a special portion of the blessing given to Abraham (Genesis 12:3); but Isaac stops short with this, and does not bestow the greater privilege that in him should all families of the earth be blessed (Genesis 12:3; Genesis 22:18; Genesis 26:4). The reason for this may be that it was a blessing which God must grant, and not man; or he may have had misgivings that it was more than Esau was worthy to receive; or, finally, his whole conduct being wrong, he could see and value only the earthly and lower prerogatives of the birthright. Subsequently he bestows the Abrahamic blessing upon Jacob in general terms (Genesis 28:4); but this, its highest privilege, is confirmed to Jacob by Jehovah Himself (Genesis 28:14).