2 Kings 2:10

And he said, thou hast asked a hard thing
Not a common privilege, but what is rarely enjoyed, and difficult to obtain, few are so favoured of God:

nevertheless, if thou see me when I am taken from thee, it shall be so
unto thee,
but if not, it shall not be so; meaning, that if his rapture was visible to Elisha, and he was favoured with a sight of his assumption, and be an eyewitness of it, this would be a token both to Elijah that it was agreeable to the Lord to ask of him this favour for him, and to Elisha to expect it, otherwise not.