John Gill Commentary 2 Kings 9:15

"but king Joram was returned to be healed in Jezreel of the wounds which the Syrians had given him, when he fought with Hazael king of Syria.) And Jehu said, If this be your mind, then let none escape and go forth out of the city, to go to tell it in Jezreel." — 2 Kings 9:15 (ASV)

But King Joram was returned to be healed in Jezreel
As is recorded, (2 Kings 8:29) and here repeated for the reason above given: and Jehu said, if it be your minds;
to engage one and all, and heartily, in this conspiracy, and to make me king: then let none go forth nor escape out of the city,
to go to tell it in Jezreel; that so Joram might be surprised unawares, and have no opportunity either of fleeing or of preparing for his defence.