1 Kings 2:4-6

4that Jehovah may confirm his word which he spoke concerning me, saying, If thy sons take heed to their way, to walk before me in truth with all their heart and with all their soul, there shall not fail thee, said he, a man upon the throne of Israel.

5And thou knowest also what Joab the son of Zeruiah did to me, what he did to the two captains of the hosts of Israel, to Abner the son of Ner, and to Amasa the son of Jether, whom he slew, and shed the blood of war in peace, and put the blood of war upon his girdle that was about his loins, and upon his sandals that were on his feet.

6And thou shalt do according to thy wisdom, and not let his hoar head go down to Sheol in peace.