The driving ... furiously - The word translated “driving” means “leading” or “conducting” a band. The watchman observed that the “company” (or, multitude) was led forward madly, and associated this strange procedure with the known character of Jehu. It is curious that some versions, as well as Josephus, give an opposite sense: “he driveth quietly.”
Jehu was properly “the grandson” of Nimshi, who was probably a more famous person than Jehoshaphat 2 Kings 9:2.