Parallel
1 Chronicles 5:1
Brenton's English Septuagint · Berean Standard Bible
And the sons of Ruben the first-born of Israel (for he [was] the first-born; but because of his going up to his father's couch, [his father] gave his blessing to his son Joseph, [even] the son of Israel; and he was not reckoned as first-born;
These were the sons of Reuben the firstborn of Israel. Though he was the firstborn, his birthright was given to the sons of Joseph son of Israel, because Reuben defiled his father’s bed. So he is not reckoned according to birthright.