2 Samuel 20:23 - Coke's Commentary on the Holy Bible

Now Joab was over all the host of Israel— Joab, having successfully put an end to the rebellion of Sheba, returned to Jerusalem to the king, and returned with such a weight of popularity, as effectually to shield his atrocious murder of Amasa from all attempts of inquiry or chastisement. "The crime," as Florus expresses it, "was within the glory:" and not only so, but reinstated him likewise in the supreme command over the army. Thus did it seem good to the divine wisdom to permit Joab's unruly and impetuous ambition, at one time separate from all sense of duty, and at another joined to it, to punish the guilt of four notorious rebels in succession, Abner, Absalom, Amasa, and Sheba, with dreadful deaths; two of them, indeed, treacherous and sudden; but all, in the retributions of Providence, judicial and just. Dr. Delaney thinks, that David published at this time the 133rd Psalm, entirely to compose all contests and disagreements among the tribes.