What does 2 Kings 9:18 mean?

So a horseman rode out to meet Jehu and said, The king wants to know if you come in peace. Jehu answered, What do you care about peace? Fall in behind me. The lookout reported, The messenger reached them, but he isn’t coming back. 2 Kings 9:18 - Modern Text Bible

(Jehu brushes off the messenger’s question and tells him to join his group. The lookout notices the messenger doesn’t return, which is suspicious.)