John Gill Bible Commentary

Now Jonathan and Ahimaaz stayed by Enrogel,.... Who were the sons of the priests; these did not go into the city of Jerusalem with their parents, when they were sent back by David, Sa2 15:27; but stayed by their direction at this place, which was near Jerusalem, and is called in the Targum the fuller's fountain, where they washed their clothes; and, as Kimchi and Jarchi say, by treading them with their feet, whence it had the name of Rogel, of which See Gill on Jos 15:7, (for they might not be seen to come into the city); having been charged by their parents to continue there for the sake of carrying intelligence to David, or because suspected by Absalom's party of carrying on such an intrigue: and a wench went and told them: what Hushai had communicated to the priests, and what was his advice to David; this girl is supposed by Kimchi and Abarbinel to be of the family of Zadok, by whom she was sufficiently instructed to tell her message, and of whom there would be no suspicion: and they went and told King David; the sons of the priests went and related to him all that had been transmitted to them.