Concise Bible Dictionary:
Jacob when dying said of Reuben “Thou art my firstborn, my might, and the beginning of my strength, the excellency of dignity, and the excellency of power.” This is what he was as the firstborn, for in himself he was “unstable as water” and he should not excel (Gen. 49:3-4). He forfeited his birth-right for defiling his father’s bed, and it was given to Joseph, who in Ephraim and Manasseh had a double portion among the tribes (1 Chron. 5:1). The law declared that if a man’s first-born son was by a wife he hated, he must not put the son of another wife in his place: the first-born must have a double portion of all that the man possessed “for he is the beginning of his strength: the right of the first-born is his” (Deut. 21:16-17). Esau is called a profane person for selling his birth-right: it was a privilege God had given him, and which he should have valued as such (Gen. 25:31-34; Heb. 12:16).
From Manners and Customs of the Bible:
Genesis 25:31,33. Jacob said, Sell me this day thy birthright.... And he sold his birthright.
Great respect was paid by the household to the first-born son. He had headship over his brothers; he succeeded to the father’s official authority; He had a special claim to the father’s benediction; in him was the progenitorship of the Messiah; the domestic priesthood belonged to him, according to some authorities, though this is denied by others. Under the Mosaic law he received a double portion of the father’s goods. This birthright could be transferred to another for a consideration, or withheld by the father for cause.
Related Books and Articles: