2 Kings 1:1 - The Popular Commentary by Paul E. Kretzmann

Then Moab rebelled against Israel, after having been tributary since the time of David, 2 Samuel 8:2, after the death of Ahab. The success of the Syrians, not only in regaining their independence, but in administering a severe defeat to the forces of Israel, had probably encouraged the Moabites to take this step.