The curse of David proves that Joab was not justified as blood-revenger or Goel 2 Samuel 3:27 in taking away Abner's life.

That leaneth on a staff - Rather, a crutch. The phrase denotes one lame or infirm. For similar instances of hereditary disease and poverty as a punishment of great sin, see 1 Samuel 2:31-33, 1 Samuel 2:36; 2 Kings 5:27; John 9:2.

Let it rest on the head - All these verbs may be rendered in the future tense: it will rest on the head of Joab, etc. This was a prophetic declaration, which sufficiently showed the displeasure of God against this execrable man.

Let it rest on the head of Joab,.... That is, the blood of Abner, who was the shedder of it; let the guilt of it be charged to him, and let punishment for it be inflicted on him:

and on all his father's house; on Abishai his brother, and other relations that might be privy to the death of Abner, and advising to it, and ready to assist in it if necessary:

and let there not fail from the house of Joab; let there be always in his family, and of his seed, one or other of the persons described as follows:

one that hath an issue; a gonorrhoea, which was reckoned infamous, and very impure, according to the Jewish law, and rendered persons unfit for society; see Leviticus 15:1,

or that is a leper; whose disease was very loathsome and infectious, and shut him out of the company of men; see Leviticus 13:1,

or that leaneth on a staff; being blind, as Aquila renders the word; or through weakness of body, not being able to walk without one; or through some disease of the feet, as the Jewish writers generally understand it; and R. Isaiah interprets it of the gout particularly: the word for "staff" is rendered "spindle", Proverbs 31:19; and to this sense it is rendered here in, the Vulgate Latin, Syriac, and Arabic versions; and then the meaning is, let his posterity, or some of them, be so poor, that they shall be obliged to get their livelihood in so mean a way as by spinning; or let them be of such an effeminate disposition, as be more fit to handle the spindle, and do the, work of women, than to use the sword:

or that falleth on the sword; not by it honourably in the field of battle, but cowardly destroying themselves with it:

or that lacketh bread; and is obliged to beg it: all which David might say, not by a spirit of prophecy, but in a passion; and to show with what horror he resented the action, and how detestable it was to him, and how far it was for him to have any concern in it: but though it was a very wicked action in Joab to murder Abner in this manner, and for the reasons he did; yet it was a just vengeance from the Lord on Abner for fighting against God, and acting against the dictates of his own conscience; for his rebellion against David, and perfidy to Ishbosheth, and for having been the cause of much bloodshed in Israel.

Let it rest on the head of Joab, and on all his father's house; and let there not fail from the house of Joab one that hath an issue, or that is a leper, or that leaneth on a staff, or that falleth on the sword, or that lacketh bread.

3:29 Let it, and c. - But would not a resolute punishment of the murderer himself have become David better, than this passionate imprecation on his posterity?

fail: Heb. be cut off

3:22-39 Judgments are prepared for such scorners as Abner; but Joab, in what he did, acted wickedly. David laid Abner's murder deeply to heart, and in many ways expressed his detestation of it. The guilt of blood brings a curse upon families: if men do not avenge it, God will. It is a sad thing to die like a fool, as they do that any way shorten their own days, and those who make no provision for another world. Who would be fond of power, when a man may have the name of it, and must be accountable for it, yet is hampered in the use of it? David ought to have done his duty, and then trusted God with the issue. Carnal policy spared Joab. The Son of David may long delay, but never fails to punish impenitent sinners. He who now reigns upon the throne of David, has a kingdom of a nobler kind. Whatever He doeth, is noticed by all his willing people, and is pleasing to them.