51 And the sons of Reuben the first-born of Israel (for he was the first-born; but, forasmuch as he defiled his father's couch, his birthright was given unto the sons of Joseph the son of Israel; and the genealogy is not to be reckoned after the birthright.
Matthew Henry's Commentary on 1 Chronicles 5:1
This chapter gives some account of the two tribes and a half seated on the east side of Jordan. They were made captives by the king of Assyria, because they had forsaken the Lord. Only two things are here recorded concerning these tribes. 1. They all shared in a victory. Happy is that people who live in harmony together, who assist each other against the common enemies of their souls, trusting in the Lord, and calling upon him. 2. They shared in captivity. They would have the best land, not considering that it lay most exposed. The desire of earthly objects draws to a distance from God's ordinances, and prepares men for destruction.