What does 1 Kings 20:42 mean?

He said to the king, 'This is what God says: You let go the man I said should be destroyed. Because of that, your life will be taken instead of his, and your people will suffer instead of his people.' 1 Kings 20:42 - Modern Text Bible

(God’s message is clear: Ahab’s mercy toward Ben-Hadad was disobedience, and now Ahab and Israel will face the consequences.)