A double portion fell to the firstborn, compare Deuteronomy 21:15-17, whence Joseph's two sons, who received the birthright forfeited by Reuben the firstborn, were counted as heads of the tribes Ephraim and Manasseh (Genesis 48:5-6; Genesis 48:22; Genesis 49:4; 1 Chronicles 5:1). The "princes" of the congregation were so probably by primogeniture (Numbers 7:2; Numbers 21:18). The rebellion of the Reubenite leaders, Dathan and Abiram, may have arisen through jealousy at the preeminence which others enjoyed above them, Reuben their first father baring had originally the primogeniture; compare Numbers 16:1-2, with Numbers 26:5-9. Esau transferred his birthright to Jacob for a paltry mess of pottage, profanely setting at nought what was the spiritual privilege connected with it, the being progenitor of the promised Messiah (Genesis 25:33; Hebrews 12:16-17).
It is striking how often God set aside the birthright, in order to show that the objects of His choice are "born not of bloods (Greek natural descents), nor of the will of the flesh, nor of the will of man, but of God" (John 1:13).Thus Isaac is preferred to Ishmael, Jacob to Esau, Joseph to Reuben, David to his elder brothers. Solomon to Adonijah the elder of the two (1 Kings 2:15). Ordinarily the firstborn inherited the throne (2 Chronicles 21:3), typifying Messiah the "first begotten" of the Father, "the Firstborn among many brethren," and Heir of all things (Romans 8:29; Hebrews 1:6). All the firstborn of Israel were claimed by Jehovah as His, He having saved them when Egypt's firstborn were slain (Exodus 22:29). He allowed them to be redeemed, and the tribe of Levi to serve Him in their stead (Numbers 3:12-13). The whole nation was God's firstborn among all the peoples (Exodus 4:22). The spiritual Israel in a still higher sense is "the church of the first born written in heaven" (enrolled as its citizens in the book of life) (Hebrews 12:23; James 1:18; Revelation 14:1-4).