What does 2 Kings 7:2 mean?

The king's right-hand man said, 'Even if God opened the windows of heaven, that couldn't happen.' Elisha answered, 'You'll see it with your own eyes, but you won't get to eat any of it.' 2 Kings 7:2 - Modern Text Bible

(The official doubts God's promise, and Elisha warns that his disbelief will keep him from sharing in the blessing.)