1 Kings 2:8-9

8Keep an eye on Shimei the son of Gera, the Benjamite from Bahurim who is with you. He called down bitter curses against me on the day I went to Mahanaim, but when he came down to meet me at the Jordan, I swore to him by the LORD: ‘I will never put you to the sword.’ 9Now therefore, do not hold him guiltless, for you are a wise man. You know what you ought to do to him to bring his gray head down to Sheol in blood.”