Act therefore according to your wisdom, but do not let his gray head go down to Sheol in peace.
Do therefore according to thy wisdom,.... Which though young began to appear in him, even in the life of his father; he therefore exhorts him to use the wisdom he had, and take the first and fittest opportunity to cut him off for his former murders and late treason, as a dangerous man to his government and the peace of it: and let not his...
Do . . . according to thy wisdom--Joab's immense popularity with the army required that any proceedings instituted against him should be taken with great prudence and deliberation.
Let not his hoar head go down to the grave in peace - It would have been an insult to justice not to have taken the life of Joab. David was culpable in delaying it so long; but probably the circumstances of his government would not admit of his doing it sooner. According to the law of God, Joab, having murdered Abner and Amasa, should die.