John Gill 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)

And it came to pass in the morning, that he went out, and
stood, and said to all the people
Who were gathered together to this shocking sight, or on the above accounts:

you are righteous ;
having had no concern in taking off the heads of those men:

behold, I conspired against my master, and slew him ;
I own it, and some may blame me for it, and charge me with treason and murder:

but who slew all these ?
not he, but the chief men of Samaria, and therefore must be more guilty than he, having shed the blood of so many persons, who had not offended against God and man to so great a degree as Joram; this he said to lessen his own sin, and wipe off the reproach of it, that his character might appear fairer in the eyes of the people, concealing, at the same time, his orders for the slaying of them.