What did King Asa do to Hanani the seer after Hanani rebuked him?

Answer: Put him in prison

Hanani rebuked Asa for relying on the king of Aram instead of the LORD; the enraged Asa put him in prison.

“Asa was angry with the seer and became so enraged over this matter that he put the man in prison. And at the same time Asa oppressed some of the people.”— 2 Chronicles 16:10 (BSB)