דברי הימים א, פרק כ״ז, פסוק ז׳

During the fourth month of the year, a dedicated military guard of twenty-four thousand men was assigned to serve. The original commander appointed to lead this division was Asahel, the brother of Joab.

A shift in leadership became necessary due to events that unfolded early in King David's reign. Asahel was killed by Abner at the very beginning of the king's rule. The primary approach among commentators is that to address this loss, the king appointed Asahel's son, Zebadiah, to fill the vacant position. Zebadiah assumed command, stepping in to lead the military division in his father's place.