John 21:21

The whole of the one is passed here to the end of this world, and there finds its termination, the other is deferred for its completion till after the end of this world, but has no end in the world to come. Hence it is said to the latter, "Follow me;" but of the former, "Thus I will that he tarry till I come, what is that to thee? follow thou me." For what means this last? So far as my wisdom goes, so far as I comprehend, what is it but this, Follow thou me by imitating me in the endurance of temporal evils; let him remain till I come to restore everlasting good? And this may be expressed more clearly in this way: Let perfected action, informed by the example of my passion, follow me; but let contemplation only begun remain [so] till I come, to be perfected when I come. For the godly plenitude of patience, reaching forward even unto death, followeth Christ; but the fullness of knowledge tarrieth till Christ come, to be manifested then.

When Peter heard this and was deemed worthy both of having the universe entrusted to him and of being crowned with martyrdom, then, out of his strong love for John, he asks about him as well: "And what about him? Will he not also go …

When Peter therefore had seen him, whom he knew to be specially beloved, he says to Jesus: Lord, but what about this man? supply: will he suffer, in order to come to you? Chrysostom: "Peter loved John greatly: because therefore the Lord had foretold great …

And so the Evangelist immediately shows Peter asking a question, When Peter saw him, he said to Jesus, Lord, what about this man? This concerns the future of John. First, we have Peter's question; Christ's answer; and then the interpretation of the answer (v 23). …

Peter hearing that he was to suffer death for Christ, asks whether John was to die: Then Peter, turning about, seeth the disciple whom Jesus loved following; which also leaned on His breast at supper, and said, Lord, which is he that betrayeth Thee? Peter seeing him saith to Jesus, Lord, and what shall this man do? i. e. Shall he not die? Or let him say, Christ did not deny that John was to die, for whatever is born dies; but said, I will that he tarry till I come, i. e. to live to the end of the world, and then he shall suffer martyrdom for Me. And therefore they confess that he still lives, but will be killed by Antichrist, and will preach Christ's name with Elias. But if his sepulchre be objected, then they say that he entered in alive, and went out of it afterwards. When our Lord says to Peter, Follow Me, He confers upon him the superintendence over all the faithful, and at the same time bids him imitate Him in every thing, word and work. He shows too His affection for Peter; for those who are most dear to us, we bid follow us. Some have understood, Till I come, to mean, Till I come to punish the Jews who have crucified Me, and strike them with the Roman rod. For they say that this Apostle lived up to the time of Vespasian, who took Jerusalem, and dwelt near when it was taken. Or, Till I come, i. e. till I give him the commission to preach, for to you I commit now the pontificate of the world: and in this follow Me, but let him remain till I come and call him, as I do thee now.

What shall this man do? - This question probably means, “What death shall he die?” But it is impossible to ascertain certainly why Peter asked this question. John was a favorite disciple, and perhaps Peter suspected that he would have a happier lot, and not be put to death in this manner. Peter was grieved at the question of Jesus; he was probably deeply affected with the account of his own approaching sufferings; and, with perhaps a mixture of grief and envy, he asked what would be his lot.

But this is very doubtful, and it seems more natural to consider our Lord as intending to give no positive indication of John's fate at all, but to signify that this was a matter which belonged to the Master of both, who would disclose or conceal it as He thought proper, and that Peter's part was to mind his own affairs.

"I tell you the solemn truth, when you were young, you tied your clothes around you and went wherever you wanted, but when you are old, you will stretch out your hands, and others will tie you up and bring you where you do not want to go." (Now Jesus said this to indicate clearly by what kind of death Peter was going to glorify God.) After he said this, Jesus told Peter, "Follow me." Peter turned around and saw the disciple whom Jesus loved following them.

"I tell you the solemn truth, when you were young, you tied your clothes around you and went wherever you wanted, but when you are old, you will stretch out your hands, and others will tie you up and bring you where you do not want to go." (Now Jesus said this to indicate clearly by what kind of death Peter was going to glorify God.) After he said this, Jesus told Peter, "Follow me." Peter turned around and saw the disciple whom Jesus loved following them. (This was the disciple who had leaned back against Jesus’ chest at the meal and asked, "Lord, who is the one who is going to betray you?") So when Peter saw him, he asked Jesus, "Lord, what about him?" Jesus replied, "If I want him to live until I come back, what concern is that of yours? You follow me!" So the saying circulated among the brothers and sisters that this disciple was not going to die. But Jesus did not say to him that he was not going to die, but rather, "If I want him to live until I come back, what concern is that of yours?" This is the disciple who testifies about these things and has written these things, and we know that his testimony is true. There are many other things that Jesus did. If every one of them were written down, I suppose the whole world would not have room for the books that would be written. These verses form the conclusion of John's Gospel, and bring to an end the most precious book in the Bible . The man is much to be pitied who can read the passage without serious and solemn feelings. It is like listening to the parting words of a friend, whom we may possibly not see again. Let us reverently consider the lessons which this Scripture contains. We learn, for one thing, from these verses, that the future history of Christians, both in life and death, is foreknown by Christ.