Then take the flask of oil, pour it on his head, and declare, ‘This is what the LORD says: I anoint you king over Israel.’ Then open the door and run. Do not delay!”
We have here the anointing of Jehu to be king, who was, at this time, a commander (probably commander-in-chief) of the forces employed at Ramoth-Gilead, Kg2 9:14. There he was fighting for the king his master, but received orders from a higher king to fight against him.
Commenting on 2 Kings 9:1-10
Then take the box of oil, and pour it on his head,.... When in the chamber together alone: and say, thus saith the Lord, I have anointed thee king over Israel; which was done, not with the anointing oil in the temple, which could not be come by; and with which, as Kimchi from their Rabbins says, only the kings of the house of David...
I have anointed thee king over Israel--This was only a part of the message; the full announcement of which is given (Kg2 9:7-10). flee, and tarry not--for fear of being surprised and overtaken by the spies or servants of the court.