A sudden succession crisis requires a careful strategy to ensure the rightful heir takes the throne. Nathan the prophet devises a coordinated, two-pronged plan to prevent Adonijah from seizing power and to secure Solomon's coronation. He instructs Bathsheba to approach King David first. Her role is to speak from a deeply personal perspective, appealing to the king as a mother anxious about the fate of her son.
Nathan assures her that while she is still in the middle of her conversation with the king, he will step into the room. His arrival is timed to seamlessly complete her thoughts, filling in any missing details and reinforcing her arguments [רלב״ג, מצודת דוד].
This dual tactic is necessary because Nathan fears that Bathsheba's personal plea alone will not be enough to spur the king into action. Adonijah is acting boldly in public, which might lead David to mistakenly believe that the prince has the broad support of the entire nation and the royal ministers. Old and physically weak, David might fear he is facing a massive uprising on the scale of Absalom's rebellion. Overwhelmed by the thought of a conflict he no longer has the strength to fight, the king might feel forced to abandon his oath to make Solomon his successor. By entering immediately after Bathsheba, Nathan intends to complete the picture. His presence adds crucial weight to her words, giving David the confidence and the decisive push he needs to act immediately [אלשיך].