Charles Ellicott Commentary 2 Samuel 20:2

"So all the men of Israel went up from following David, and followed Sheba the son of Bichri; but the men of Judah clave unto their king, from the Jordan even to Jerusalem." — 2 Samuel 20:2 (ASV)

Men of Judah clave. —David’s negotiations with Judah had now resulted in an entire reversal of the position of the tribes towards him; Judah, among whom the rebellion originated, and who had been tardy in returning to their allegiance, were now fierce in their loyalty, while Israel, who had only joined the already organized rebellion, and afterwards had first proposed the return of David, had become alienated and rebellious.