(Vs. 18-19) Verse 19 gives us the meaning of our Lord's words to Peter in Verse 18. Peter (as all of the apostles except John, who was exiled to Patmos) would die a martyr. The Lord tells him by what death he would glorify God–crucifixion! When you were young, you freely dressed yourself and traveled where you would in freedom. But you will live to be an old man, preaching the gospel of God's grace and feeding the sheep of Christ: and then you will be bound as a prisoner, stretching forth your hands on n cross; and they will take you to a shameful, cruel death. "Where thou wouldest not" means NOT that Peter would be unwilling to die for Christ, but that this type of death is disagreeable to the flesh. Our Lord glorified the Father in death (John 13:31-32), and the disciples would also glorify God in their deaths (II Peter 1:14).It is reported in "Fox's Book of Martyrs" that:
The lord said to Peter, "Follow Me," in preaching the gospel and in death. Our Lord renewed the call He had given to Peter earlier (Matt. 4:18-20).
(Vs. 20-21.) Peter looked over at John, the writer of this book, who (without calling his own name) describes himself so as to leave no doubt as to whom Peter meant. "Lord, what shall John do? What shall John suffer?" It is really difficult to determine the reason Peter asked this of Christ. Was he genuinely concerned for his friend John? Was he just curious about John's future service and usefulness? Or was he thinking, "If I am to be a prisoner and die for the faith, should not John and the others suffer also? Am I the only one who shall bear the wrath of men for the glory of God?" From the answer that our Lord gave to Peter, we can determine that the question was impertinent, improper, and totally out of place. Evidently our Lord's command, "You follow Me," had not registered fully with Peter.
(Vs. 22) The Lord's reply carries a strong rebuke for Peter's curiosity, friendly interest, probing into secret matters, or whatever it was that motivated Peter's question. "If it is My will for John to live and not die until I return, of what concern is that to you? YOU FOLLOW ME!" While the body of Christ is made up of many members and our ONE COAL AND PURPOSE is to glorify our head, Jesus Christ–to preach His Word, to feed 1tis sheep, and to follow Him--yet the work each member does, the gifts each member has, the place each occupies, and the suffering each endures are according to the will and purpose of the Lord. We must be occupied with our own ministry, calling, and faithfulness to Christ and not be taken up with how, when, or where He is pleased to use others (I Cor. 12:12-27). There should be no jealousy, envy, nor self-seeking among the servants of the great King. In His infinite wisdom and according to His purpose, He calls and assigns each servant to his place and work, which work is to be done willingly, diligently, and unto the Lord (II Tim. 2:9-10).
(Vs. 23-24) I suppose that it is only normal and natural (men being what they are, always ready to misinterpret, misread, and misapply the Word of the Lord) that the rumor went forth among the brethren (and remained for a long time) that John would not die but would remain until the second coming of the Lord Jesus. But John, who wrote this epistle (and we know that his testimony is correct), sets the record straight. The Lord did not say that John would not die! In answer to Peter's concern for what place John would serve and what death John would die, the Lord said, "IF IT IS MY WILL for John to live until I come and never die, that is of no concern to you, Peter; it is your business to follow Me and fulfil My purpose, whatever I am pleased to do with John."
(Vs. 25) We must never imagine that all that our Saviour did and said are recorded in this book or in any other book. If all the miracles He did, sermons He preached, works He performed, and words He spoke had been written in books, the world itself could not contain the books that must be written: for He is from everlasting to everlasting! However, God has been pleased to have written all that is necessary and needful for us to know concerning the person and work of the Lord Jesus Christ, that we may know Him, believe Him, and be brought to life eternal (John 20:31; II Tim. 3:15-17).