Now Jonathan and Ahimaaz stayed by En-rogel; for they might not be seen to come into the city: and a wench went and told them; and they went and told king David.
We must now leave David's enemies pleasing themselves with the thoughts of a sure victory by following Hushai's counsel, and sending a summons, no doubt, to all the tribes of Israel, to come to the general rendezvous at a place appointed, pursuant to that counsel; and we next find David's friends consulting how to get him notice of all this, that he might steer his course accordingly.
Commenting on 2 Samuel 17:15-21
Nevertheless, a lad saw them, and told Absalom,.... Saw them conversing with the girl, and departing for David's army; according to Josephus (o), they were some horsemen that saw them about two furlongs or a quarter mile from Jerusalem, and acquainted Absalom with it: but they went both of them away quickly; made all the haste they could with their message to David: and came...
by En-rogel--the fuller's well in the neighborhood of Jerusalem, below the junction of the valley of Hinnom with that of Jehoshaphat.