5:1
The Genealogy of the Trans-Yardan Tribes and the Fractured Birthright
Now the sons of Ra'uban the firstborn of Yashar'al, (for he was the firstborn; but, forasmuch as he defiled his father's bed, his birthright was given unto the sons of Yusaph the son of Yashar'al: and the genealogy is not to be reckoned after the birthright.