John Gill Bible Commentary

The matter is not so,.... I am not come with the army against this city with any ill will to it, and with an intention to destroy it: the case is this: but a man of Mount Ephraim, Sheba the son of Bichri by name; for though he was by birth a Benjaminite, his dwelling was in Mount Ephraim in that tribe; unless there was a place of this name in the tribe of Benjamin, so called from any memorable event there, as the wood of Ephraim, Sa2 18:6. This same man, says Joab: hath lifted up his hand against the king, even against David; is in rebellion against the king, even so great and good a king as David; he has lifted up his hand, and blown a trumpet to draw off men from David, and after himself; he has committed acts of hostility and treason; he has drawn his sword, and raised an insurrection and rebellion in the nation: deliver him only, and I will depart from the city: he did not desire any of his followers to be delivered up, only himself, knowing the rebellion would cease upon the delivery of him; and being unwilling that the blood of any Israelite should be shed, whom he had unawares drawn into this rebellion, and who he knew would return to their own cities upon this: and the woman said unto Joab, behold, his head shall be thrown to thee over the wall; she knew the fright the inhabitants of the city were in, and how disposed they were to do anything to save their city; she knew what influence she had among them, and how weak Sheba's party was, and therefore could assure Joab that this should be done.