John 6:62 - Ellicott's Commentary On The Whole Bible

What and if ye shall see ...? — Our version adds the word “what,” as will be seen from the italics, but it rightly expresses the sense. Literally, we should read, If then ye should behold the Son of Man ascending up where He was before? The Ascension would be the proof of the coming down from heaven (John 6:58), which is part of the teaching they cannot now accept. The margin refers to the more formal statement of this in John 3:13. The reader should also compare John 20:17, where the Ascension is again assumed, and Ephesians 4:9-10. Comments on these incidental references by St. John to an event he does not record have been made too frequently without noting that, in each case, the speaker is Jesus, to whose thoughts this end of subjection to earthly laws, in subjecting them to Himself, was ever present. St. John, in his own narrative, nowhere mentions the fact of the Ascension, nor does he in any way refer to it. That he could write these words without doing so is an assurance of his own knowledge of the glorious sequel of the Resurrection, and of its unquestioned acceptance in the Church.