Albert Barnes Commentary 2 Kings 10:9

"And it came to pass in the morning, that he went out, and stood, and said to all the people, Ye are righteous: behold, I conspired against my master, and slew him; but who smote all these?" — 2 Kings 10:9 (ASV)

You are righteous - that is, “You are just, and can judge rightly.” Jehu unfairly keeps back the fact that he had commanded the execution.