60 Many therefore of his disciples, when they had heard this, said, This is an hard saying; who can hear it? 61 When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you? 62 What and if ye shall see the Son of man ascend up where he was before? (John 6:60-62 KJV)
William Burkitt’s Commentary
The foregoing doctrine of our Saviour concerning eating his flesh and drinking his blood, sounded so very harshly, that not only the common multitude, but some of them that had been his disciples, that is, who had given up their names to follow him, could not tell how to hear it. Our Saviour reproves their unjust stumbling at what he had said, that he was the bread which came down from heaven, and tells them, that his ascension into heaven should prove the truth of his descent from heaven.
Hence we learn, That Christ’s arising from the grave, and ascending into heaven, by his own power is an evident proof of his godhead, and that he really came down from heaven, in respect of his divine nature, which condescended to be clothed with our flesh. What and if ye shall see the Son of man ascend up where he was before?