1 Kings 2:5
Moreover thou knowest also what Joab the son of Zeruiah did to me, and what he did to the two captains of the hosts of Israel, unto Abner the son of Ner, and unto Amasa the son of Jether, whom he slew, and shed the blood of war in peace, and put the blood of war upon his girdle that was about his loins, and in his shoes that were on his feet.
The verse belongs to David's counsel to Solomon concerning men unworthy of confidence and trust, Joab among them, whom Solomon was to deal with according to wisdom received from God. David knew Joab was not a man who loved or feared God, yet he clung to him because Joab appeared unswervingly loyal and ready to do whatever David commanded. He did not himself condemn Joab's wrongs but left that work to Solomon, declaring that Joab must not go down to the grave in peace.
The counsel shows that disaffection, unfaithfulness, scheming, and deception are not virtues, and that those entrusted with God's work must oppose them decisively, meeting unfaithfulness with firm disapproval in business matters as well as in spiritual things. Counsel in temporal affairs, and especially in sacred matters, is therefore to be entrusted only to persons worthy of the fullest confidence.