1 Kings 2:5-9

5Now you also know what Joab the son of Zeruiah [my sister] did to me, and what he did to the two commanders of the armies of Israel, to Abner the son of Ner and to Amasa the son of Jether, [both of] whom he murdered; avenging the blood of war in [a time of] peace. And he put the [innocent] blood of war [of Abner and Amasa] on his belt that was around his waist, and on his sandals on his feet.

6So act in accordance with your wisdom, but do not let his gray head go down to Sheol (the place of the dead) in peace.

7But be gracious and kind to the sons of Barzillai the Gileadite, and let them be among those who [have the honor to] eat at your table; for they met me [with kindness] when I fled from your brother Absalom.

8And look, you have with you Shimei the son of Gera, the Benjamite of Bahurim; he is the one who cursed me with a sinister curse the day I went to Mahanaim. But he came down to meet me at the Jordan [on my return], and I swore to him by the Lord, saying, ‘I will not put you to death with the sword.’

9But now do not let him go unpunished, for you are a wise man; and you will know what to do to him, and you will bring his gray head down to Sheol [covered] with blood.”