The transfer of royal power is a moment that requires more than just political obedience. When David announces that Solomon will take the throne, Benaiah steps forward to offer a response that blends total acceptance with a deep prayer for the plan's success. By firmly affirming the decision, he expresses a strong hope that the royal decree will truly come to pass [מצודת ציון, ביאור שטיינזלץ]. More specifically, this confirmation serves as a sincere prayer that Solomon will be granted a long life [רש״י].
Human approval, however, is not enough. Beyond his own agreement, Benaiah adds a plea that God will also endorse the decree. This is a prayer that the decision made on earth will receive full backing and approval in heaven [מלבי״ם]. He recognizes that unless it is truly God's will for Solomon to sit on the throne, David's earthly declaration will ultimately be useless [רלב״ג, מצודת דוד].
Among everyone present, Benaiah chooses to go beyond simply confirming the king's orders by adding his own personal blessing. This serves as an introduction to his greater wish: that God will be with Solomon just as He was with David, and even make Solomon's reign greater than his father's. On the surface, hoping that a new king will outshine the current one might seem disrespectful to the reigning monarch. Yet, Benaiah speaks from a place of deep human and spiritual insight, knowing that a father is never jealous of his own son's success [אברבנאל].