Albert Barnes Commentary 2 Chronicles 25:16

"And it came to pass, as he talked with him, that [the king] said unto him, Have we made thee of the king`s counsel? forbear; why shouldest thou be smitten? Then the prophet forbare, and said, I know that God hath determined to destroy thee, because thou hast done this, and hast not hearkened unto my counsel." — 2 Chronicles 25:16 (ASV)

Are you a member of the king’s council? - A subtle irony: “Have I made you a member of my council? If not, what entitles you to offer your advice?”

For the fulfillment of the prophecy, see 2 Chronicles 25:22–24, 2 Chronicles 25:27.