2-а Самуїлова 4:12

David then commanded his servant to slay the murderers, and also to make the punishment more severe than usual. "They cut off their hands and feet," - the hands with which they had committed the murder, and the feet which had run for the reward, - "and hanged the bodies by the pool at Hebron" for a spectacle and warning, that others might be deterred from committing similar crimes (cf. Deu 21:22; J. H. Michaelis). In illustration of the fact itself, we may compare the similar course pursued by Alexander towards the murderer of king Darius, as described in Justin's history (Sa2 12:6) and Curtius (Sa2 7:5). They buried Ishbosheth's head in Abner's grave at Hebron. Thus David acted with strict justice in this case also, not only to prove to the people that he had neither commanded nor approved of the murder, but from heartfelt abhorrence of such crimes, and to keep his conscience void of offence towards God and towards man.

When Abner was slain David was at a loss for a friend to perfect the reduction of those tribes that were yet in Ish-bosheth's interest. Which way to adopt for the accomplishment of it he could not tell; but here Providence brings it about by the removal of Ish-bosheth. I. Two of his own servants slew him, and brought his head to David (Sa2 4:1-8). II. David, instead of rewarding them, put them to death for what they had done (Sa2 4:9-12).

4:12 cut off their hands and feet: Displaying the dismembered bodies of Ishbosheth’s killers shamed them by denying them proper burial (cp. 1 Sam 31:8-13); it was also a public testimony of David’s innocence in Ishbosheth’s death.