That “one tribe” promised by the Lord is Solomon’s own tribe, Judah. But by the time this is written several centuries later, Judah is the common name for the Southern Kingdom, which is ruled by Solomon’s descendants and actually composed of two tribes: Judah and Benjamin. Ironically Benjamin and Judah were historically enemies. As the tribe of Saul, Benjamin was predisposed against David when he became king, and they continued their animosity toward him by supporting Absalom during his rebellion. All of those bad feelings will change when Judah and Israel split. Benjamin will decide to follow Rehoboam along with Judah, while the other ten tribes will follow Jeroboam.