John Gill Commentary 2 Kings 9:17

"Now the watchman was standing on the tower in Jezreel, and he spied the company of Jehu as he came, and said, I see a company. And Joram said, Take a horseman, and send to meet them, and let him say, Is it peace?" — 2 Kings 9:17 (ASV)

And there stood a watchman on the tower of Jezreel
Who could see afar off when an enemy was coming, and his business was to give notice of it; and especially he was now on his watch tower, because the king was there, and this was necessary for his safety: and he spied the company of Jehu as he came, and said, I see a
company ;
a troop of soldiers, though he did not know who they were, and to whom they belonged, whether they were Syrians or Israelites; which was reported to the king:

and Joram said, take an horseman, and send to meet them, and let him
say, is it peace ?
he might fear some ill had befallen his army at Ramothgilead, and the Syrians had got the advantage of them; or they had made an irruption into his country, and were coming to attack him at Jezreel; or there was an insurrection among his own people.