1 Kings 2:8-9

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.