At the same time his relative Abner kept strengthening himself at the expense of Ish-bosheth, even to the point of having relations with one of Saul’s concubines, which, according to Oriental custom, was tantamount to treason. When rebuked for this by Ish-bosheth, Abner withdrew his support and made a covenant with David, part of which stipulated the return of David’s wife, Michal, who was Ish-bosheth’s own sister. (2Sa 3:6-21)

After the death of Saul and his other sons on the battlefield at Gilboa, Abner, a relative of Saul and the chief of his forces, took Ish-bosheth across the Jordan to Mahanaim, where he was installed as king over all the tribes except Judah, which recognized David as king.