2 Samuel 3:39
And I am this day weak, though anointed king; and these men the sons of Zeruiah be too hard for me: the LORD shall reward the doer of evil according to his wickedness. And I am this day weak, though anointed king; and these men the sons of Zeruiah be too hard for me: the LORD shall reward the doer of evil according to his wickedness.
David spoke these words in private among his trusted counselors and attendants concerning the murder of Abner. In that private circle he honored Abner as a prince and a great man, showing generous honor toward one who had been his bitter enemy. That generosity won the confidence and admiration of all Israel. It convinced the people that he had no part in the killing.
By calling himself weak though anointed king, he acknowledged that he was unable to punish the murderers as he desired. He therefore left them to the justice of God to repay evil for evil.