One of Joab’s men, left there on purpose to deliver the following message.
He that favoureth Joab; he that would have Joab to be general, rather than such a perfidious rebel and traitor as Amasa.
He that is for David; he that wisheth David good success against Sheba, and against all rebels; whereby he implies that though this fact of his was done against the king’s command, yet it was for his interest and defence.