1 Kings 2:7 (KJV)

Moreover thou knowest also what Joab the son of Zeruiah did to me, and what he did to the two captains of the hosts of Israel, unto Abner the son of Ner, and unto 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 in his shoes that were on his feet.

Do therefore according to thy wisdom, and let not his hoar head go down to the grave in peace.

But shew kindness unto the sons of Barzillai the Gileadite, and let them be of those that eat at thy table: for so they came to me when I fled because of Absalom thy brother.

And, behold, thou hast with thee Shimei the son of Gera, a Benjamite of Bahurim, which cursed me with a grievous curse in the day when I went to Mahanaim: but he came down to meet me at Jordan, and I sware to him by the Lord, saying, I will not put thee to death with the sword.

Now therefore hold him not guiltless: for thou art a wise man, and knowest what thou oughtest to do unto him; but his hoar head bring thou down to the grave with blood.