I Chronicles 5:1

Now the sons of Reuben, the firstborn of Israel,.... Are as follow in Ch1 5:3 where the account begins; for what comes between this and that is in a parenthesis: for he was the firstborn; of Jacob by his wife Leah; that must be owned, and Jacob allows it, Gen 49:3 and yet the genealogy in this book begins not with him, as might on that account be expected; the reason follows: but forasmuch as he defiled his father's bed: by lying with Bilhah his concubine: his birthright was given unto the sons of Joseph the son of Israel; his beloved son by his beloved wife Rachel and so had a double portion given him; his two sons being equally ranked with the other sons of Jacob, and became distinct tribes, and each had their lot in the land of Canaan, see Gen 48:5 compared with Deu 21:17. and the genealogy is not to be reckoned after the birthright; or, "but the genealogy", &c. (o); neither after the birthright of Reuben, which he had by nature, being Jacob's firstborn; nor after the birthright of Joseph, which be had by his father's gift, as it might be thought it should; the reason of which follows. (o) "Nee tamen", Tigurine version.

We have here an extract out of the genealogies, I. Of the tribe of Reuben, where we have, 1. The reason why this tribe is thus postponed. It is confessed that Reuben was the first-born of Israel, and, upon that account, might challenge the precedency; but he forfeited his birthright by defiling his father's concubine, and was, for that, sentenced not to excel, Gen 49:4. Sin lessens men, thrusts them down from their excellency. Seventh-commandment sins especially leave an indelible stain upon men's names and families, a reproach which time will not wipe away. Reuben's seed, to the last, bear the disgrace of Reuben's sin. Yet, though that tribe was degraded, it was not discarded or disinherited. The sullying of the honour of an Israelite is not the losing of his happiness. Reuben loses his birthright, yet it does not devolve upon Simeon the next in order; for it was typical, and therefore must attend, not the course of nature, but the choice of grace. The advantages of the birthright were dominion and a double portion. Reuben having forfeited these, it was thought too much that both should be transferred to any one, and therefore they were divided. (1.) Joseph had the double portion; for two tribes descended from him, Ephraim and Manasseh, each of whom had a child's part (for so Jacob by faith blessed them, Heb 11:21; Gen 48:15, Gen 48:22), and each of those tribes was as considerable, and made as good a figure, as any one of the twelve, except Judah. But, (2.) Judah had the dominion; on him the dying patriarch entailed the sceptre, Gen 49:10 Of him came the chief ruler, David first, and, in the fulness of time, Messiah the Prince, Mic 5:2. This honour was secured to Judah, though the birthright was Joseph's; and, having this, he needed not envy Joseph the double portion.…

5:1-24 Chapter 5 records the genealogies for Reuben (5:1-10; cp. Gen 46:9), Gad (1 Chr 5:11-17), and Manasseh (5:23-24), the tribes of Israel that settled in Transjordan (the area east of the Jordan River). 5:1-2 Although Reuben was the oldest son of Israel, he did not receive his birthright because he had sexual relations with his father’s concubine (Gen 35:22). Jacob transferred this right to Joseph when he elevated Ephraim and Manasseh to full membership among the tribes (Gen 48:5). This gave Joseph the double portion that traditionally belonged to the firstborn (Deut 21:15-17). As Jacob foresaw, Judah surpassed his brothers and became the forefather of the ruling tribe (Gen 49:8-10). However, Reuben is still listed first (1 Chr 2:1).