2 Samuel 2:10

10. Ishbosheth… reigned two years The next verse informs us that David reigned in Hebron ever Judah seven years and six months, and therefore we must naturally conclude that for five years and six months the other tribes of Israel were without an acknowledged king. It is altogether gratuitous to assume, as some critics have done, that Ishbosheth reigned all the time that David reigned in Hebron. It is probable, however, that David was king in Hebron some time before Ishbosheth began to reign. David seems to have been anointed very soon after Saul’s death, but it must have taken Abner some time to gather up the scattered army and recover from the defeat and losses of Gilboa sufficiently to attend to the inauguration of Ishbosheth. So it is likely that David reigned in Hebron a year or more before the son of Saul was anointed at Mahanaim. Then followed two years of strife and bickering between the two governments, which was of sufficient length to be called “long war.” 2 Samuel 3:1. And after both Abner and Ishbosheth had been vilely assassinated, it is but natural to suppose that the northern tribes would wait some years to observe the manner of David’s government before they all came together to acknowledge and anoint him king. See on 2 Samuel 5:1.