1 Kings 2:4-6

4so that the Lord may fulfill His promise concerning me, saying, ‘If your sons are careful regarding their way [of life], to walk before Me in truth with all their heart and mind and with all their soul, you shall not fail to have a man (descendant) on the throne of Israel.’

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.