Albert Barnes Commentary 2 Kings 8:10

"And Elisha said unto him, Go, say unto him, Thou shalt surely recover; howbeit Jehovah hath showed me that he shall surely die." — 2 Kings 8:10 (ASV)

The verse can be translated: Go, say to him, You will certainly live; however, the Lord has shown me that he will certainly die. This means, “Say to him what you have already determined to say—what a courtier is sure to say (compare 1 Kings 22:15)—but know that the fact will be otherwise.”