1 Kings 2:8-9

8“And see, you have with you Shimei the son of Gera, a Benjamite from Bahurim, who cursed me with a malicious curse in the day when I went to Mahanaim. But he came down to meet me at the Jordan, and I swore to him by the Lord, saying, ‘I will not put you to death with the sword.’

9Now therefore, do not hold him guiltless, for you are a wise man and know what you ought to do to him; but bring his gray hair down to the grave with blood.”