And the prophet said to the king, “This is what the LORD says: ‘Because you have let slip from your hand the man I had devoted to destruction, your life will be exchanged for his life, and your people for his people.’”
The prophet declares the LORD's word: because Ahab let go the man devoted to destruction, his life will answer for that life, and his people for that people.
It delivers the chapter's judgment on Ahab's release of Ben-hadad.
35Meanwhile, by the word of the LORD, one of the sons of the prophets said to his companion, “Strike me, please!” 36Then the prophet said to him, “Because you have not obeyed the voice of the LORD, as soon as you depart from me a lion will kill you.” 37Then the prophet found another man and said, “Strike me, please!” 38So the man struck him and wounded him, and the prophet went and waited on the road for the king, disguising himself with a bandage over his eyes. 39As the king passed by, he cried out to the king: “Your servant had marched out into the middle of the battle, when suddenly a man came over with a captive and told me, ‘Guard this man! If he goes missing for any reason, your life will be exchanged for his life, or you will weigh out a talent of silver. ’ 40But while your servant was busy here and there, the man disappeared.” 41Then the prophet quickly removed the bandage from his eyes, and the king of Israel recognized him as one of the prophets. 42And the prophet said to the king, “This is what the LORD says: ‘Because you have let slip from your hand the man I had devoted to destruction, your life will be exchanged for his life, and your people for his people.’” 43Sullen and angry, the king of Israel went home to Samaria.