Charles Ellicott Commentary 2 Kings 5:10

"And Elisha sent a messenger unto him, saying, Go and wash in the Jordan seven times, and thy flesh shall come again to thee, and thou shalt be clean." — 2 Kings 5:10 (ASV)

Elisha sent a messenger. —This was to avoid personal contact with a leper. (Compare to 2 Kings 5:15, where Naaman, when restored, goes in and stands before the prophet.) Perhaps reverence held back those who consulted a great prophet from entering his presence (compare to 2 Kings 4:12); and therefore, Naaman stopped with his followers outside the house. Keil suggests that Elisha did not come out to Naaman because he wished to humble his pride and to show that his worldly magnificence did not impress the prophet. But, as Thenius says, there is no trace of pride about Naaman.

Go. —This is an infinitive, equivalent to the imperative. (Compare to 2 Kings 3:16; and perhaps 2 Kings 4:43.)

Wash in (the) Jordan. —This command would make it clear that Naaman was not cured by any external means applied by the prophet. “The Syrians knew as well as the Israelites that the Jordan could not heal leprosy” (Bähr). Naaman was to understand that he was healed by the God of Israel, at His prophet’s prayer. (Compare to 2 Kings 5:15.)

Thy flesh shall come again to thee, and thou shalt be clean. —Literally, and let your flesh come back to you, and you be clean. Leprosy is characterized by raw flesh and running sores, which end in an entire wasting away of the tissues.