Matthew Henry on 2 Samuel 20:4-13
We have here Amasa's fall just as he began to rise. He was nephew to David (Sa2 17:25), had been Absalom's general and commander-in-chief of his rebellious army, but, that being routed, he came over into David's interest, upon a promise that he should be general of his forces instead of Joab. Sheba's rebellion gives David an occasion to fulfil his promise sooner than he could wish, but Joab's envy and emulation rendered its fulfillment of ill consequence both to him and David.
I. Amasa has a commission to raise forces for the suppressing of Sheba's rebellion, and is ordered to raise them with all possible expedition, Sa2 20:4. It seems, the men of Judah, though forward to attend the king's t…
Read the whole note in the consoleJamieson-Fausset-Brown on 2 Samuel 20:11
He that favoureth Joab, and he that is for David, let him go after Joab--It is a striking proof of Joab's unrivalled influence over the army, that with this villainous murder perpetrated before their eyes they unanimously followed him as their leader in pursuit of Sheba. A soldier conjoined his name with David's, and such a magic spell was in the word "Joab," that all the people "went on"--Amasa's men as well as the rest. The conjunction of these two names is very significant. It shows that the one could not afford to do without the other--neither Joab to rebel against David, nor David to get rid of Joab, though hating him.
Adam Clarke on 2 Samuel 20:11
He that favoureth Joab - As if he had said, There is now no other commander besides Joab; and Joab is steadily attached to David: let those therefore who are loyal follow Joab.
John Gill on 2 Samuel 20:11
And one of Joab's men stood by him,.... By the body of Amasa; no doubt by the order of Joab, to satisfy the people as they came up, and reconcile them to this fact, and to exhort them not to stop, but to follow after Joab; for though Amasa their general was dead, Joab had taken the command of the army, and the pursuit was carried on with as much rigour as ever:
and said, he that favoureth Joab, and he that is for David, let him go after Joab: he that likes Joab should be general, and is in the interest of David, let him make no stay here, but follow after Joab; Joab and David are put together, as if their interests were the same; though there seems to be an indecency in placing Joab first.