Charles Ellicott Commentary 2 Samuel 3:7

"Now Saul had a concubine, whose name was Rizpah, the daughter of Aiah: and [Ish-bosheth] said to Abner, Wherefore hast thou gone in unto my father`s concubine?" — 2 Samuel 3:7 (ASV)

Rizpah. —The name of this woman is associated with her strong and tender grief over the loss of her sons, recorded in 2 Samuel 21:8–11.

Why have you gone in? —The harem of an Eastern monarch was considered the property of his successor, and therefore taking a woman belonging to it was also considered an assertion of a claim to the throne. (See 2 Samuel 12:8; 2 Samuel 16:21; 1 Kings 2:22.)

It is not probable that Abner had any such design, since he was exerting himself to maintain Ish-bosheth on the throne. But the king appears to have regarded the act in this way, since it is this implied charge of treachery that so greatly rouses Abner's anger. The name of Ish-bosheth has dropped out of the Hebrew text, but appears in a few manuscripts, and is rightly restored in all the versions.