1 Kings 1:44
And the king hath sent with him Zadok the priest, and Nathan the prophet, and Benaiah the son of Jehoiada, and the Cherethites, and the Pelethites, and they have caused him to ride upon the king’s mule: And the king hath sent with him Zadok the priest, and Nathan the prophet, and Benaiah the son of Jehoiada, and the Cherethites, and the Pelethites, and they have caused him to ride upon the king’s mule:
David arranged Solomon's succession by sending trusted religious and military leaders with him, including Zadok the priest and Nathan the prophet together with Benaiah the son of Jehoiada and the Cherethites and the Pelethites. This escort gave Solomon the sanction of both the sacred office and the armed force of the kingdom at the moment of transfer. David further directed that Solomon be caused to ride upon the king's own mule. That public act marked Solomon as the chosen king, displaying before the people that the authority of David now rested upon him.