Let it rest on the head of Joab. — The strong curse here pronounced by David shows that Joab’s act could not be justified as that of the “Goel,” or lawful avenger of his brother’s blood, for Abner had slain Asahel in battle, unwillingly and in self-defence. It is also to be remembered that Hebron was a city of refuge (Joshua 21:13), and that here not even the “Goel” might slay the murderer without a trial (Numbers 35:22-25). The curse falls “on his father’s house,” since Abishai also (2 Samuel 3:30) had been concerned with him in the murder.
The phrase, “that leaneth on a staff,” has been understood by many as “holding a distaff,” i.e., a person unfit for war. The word has the sense of “distaff” in Proverbs 31:19, and is so rendered here by the Vulgate; but the sense given by the English — which is also that of the LXX. and Targum — is better, and more in accordance with the other particulars.
For “on the sword” read “by the sword,” there being no reference to the idea of suicide. On the violent end of Joab see 1 Kings 2:31-34.