Lamented - i. e. composed and sang the funeral dirge which follows (compare 2-Samuel 1:17).
Died Abner - i. e. The great and noble and valiant Abner had died as ignobly and as helplessly as the meanest churl!

The king lamented over Abner - This lamentation, though short, is very pathetic. It is a high strain of poetry; but the measure cannot be easily ascertained. Our own translation may be measured thus: -
Died Abner as a fool dieth?
Thy hands were not bound,
Nor thy feet put into fetters.
As a man falleth before the wicked.
So hast thou fallen!
Or thus: -
Shall Abner die a death like to a villain's?
Thy hands not bound,
Nor were the fetters to thy feet applied.
Like as one falls before the sons of guilt,
So hast thou fallen!
He was not taken away by the hand of justice, nor in battle, nor by accident: he died the death of a culprit by falling into the hands of a villain.
This song was a heavy reproof to Joab; and must have galled him extremely, being sung by all the people.

And the king lamented over Abner, and said, Died Abner (n) as a fool dieth?
(n) He declares that Abner died not as a wretch or vile person, but as a valiant man might do, being traitorously deceived by the wicked.

And the king lamented over Abner,.... Delivered an elegy or funeral oration, which he had composed on this occasion, as Josephus (u) suggests: for he had cried and wept before, but now he expressed something as follows:
and said, died Abner as a fool dieth? the meaning of the interrogation is, he did not; the Targum is"did Abner die as wicked men die?''no, he did not; he did not die for any wickedness he had been guilty of; he did not die as a malefactor, whose crime has been charged and proved in open court, and sentence of condemnation pronounced on him righteously for it; but he died without anything being laid to his charge, and much less proved, and without judge or jury; he was murdered in a clandestine, insidious, and deceitful manner; so the word "fool" is often taken in Scripture for a wicked man, especially in the book of Proverbs; the Septuagint version leaves the word untranslated,"died Abner according to the death of Nabal?''no; but it could hardly be thought that David would mention the name of any particular person on such an occasion.
(u) Ut supra. (Antiqu. l. 7. c. 1. sect. 6.)

the king lamented over Abner--This brief elegy is an effusion of indignation as much as of sorrow. As Abner had stabbed Asahel in open war [2-Samuel 2:23], Joab had not the right of the Goel. Besides, he had adopted a lawless and execrable method of obtaining satisfaction (see on 1-Kings 2:5). The deed was an insult to the authority, as well as most damaging to the prospects of the king. But David's feelings and conduct on hearing of the death, together with the whole character and accompaniments of the funeral solemnity, tended not only to remove all suspicion of guilt from him, but even to turn the tide of popular opinion in his favor, and to pave the way for his reigning over all the tribes more honorably than by the treacherous negotiations of Abner.

As a fool - That is, as a wicked man. Was he cut off by the hand of justice for his crimes? Nothing less; but by Joab's malice and treachery. It is a sad thing to die as a fool dieth, as they do that any way shorten their own days: and indeed all they that make no provision for another world.