Of the Proof of Their Freedom from Any Discrepancies in the Notices Given of the Predictions of Peter's Denials
5 “Little children, yet a little while I am with you. You shall seek me: and, as I said unto the Jews, Whither I go, you cannot come; so now I say unto you. A new commandment I give unto you, That ye love one another; as I have loved you, that you also love one another. By this shall all men know that you are my disciples, if you have love one to another. Simon Peter says unto Him, Lord, where are you going? Jesus answered him, Whither I go, you can not follow me now, but you shall follow me afterwards. Peter says unto Him, Lord, why cannot I follow You now? I will lay down my life for Your sake. Jesus answered him, Will you lay down your life for my sake? Verily, verily, I say unto you, The cock shall not crow, until you deny me thrice.” John, from whose Gospel I have taken the passage introduced above, is not the only evangelist who details this incident of the prophetic announcement of his own denial to Peter. The other three also record the same thing. They do not, however, take one and the same particular point in the discourses [of Christ] as their occasion for proceeding to this narration. For Matthew and Mark both introduce it in a completely parallel order, and at the same stage of their narrative, namely, after the Lord left the house in which they had eaten the passover; while Luke and John, on the other hand, bring it in before He left that scene. Still we might easily suppose, either that it has been inserted in the way of a recapitulation by the one couple of evangelists, or that it has been inserted in the way of an anticipation by the other; only such a supposition may be made more doubtful by the circumstance that there is so remarkable a diversity, not only in the Lord's words, but even in those sentiments of His by which the incident in question is introduced, and by which Peter was moved to venture his presumptuous asseveration that he would die with the Lord or for the Lord. These considerations may constrain us rather to understand the narratives really to import that the man uttered his presumptuous declaration thrice over, as it was called forth by different occasions in the series of Christ's discourses, and that also three several times the answer was returned him by the Lord, which intimated that before the cock crew he would deny Him thrice.
6. And surely there is nothing incredible in supposing that Peter was moved to such an act of presumption on several occasions, separated from each other by certain intervals of time, as he was actually instigated to deny Him repeatedly. Neither should it seem unreasonable to fancy that the Lord gave him a reply in similar terms at three successive periods, especially when [we see that] in immediate connection with each other, and without the interposition of anything else either in fact or word, Christ addressed the question to him three several times whether he loved Him, and that, when Peter returned the same answer thrice over, He also gave him thrice over the self-same charge to feed His sheep. That it is the more reasonable thing to suppose that Peter displayed his presumption on three different occasions, and that thrice over he received from the Lord a warning with respect to his triple denial, is further proved, as we may see, by the very terms employed by the evangelists, which record sayings uttered by the Lord in diverse form and of diverse import. Let us here call attention again to that passage which I introduced a little ago from the Gospel of John. There we certainly find that He had expressed Himself in this way: “Little children, yet a little while I am with you. You shall seek me: and as I said unto the Jews, Whither I go, you cannot come; so now I say to you. A new commandment I give unto you, That ye love one another; as I have loved you, that you love one another. By this shall all men know that you are my disciples, if you have love one to another. Simon Peter says unto Him, Lord, where are You going?” Now, surely it is evident here that what moved Peter to utter this question, “Lord, where are You going?” was the words which the Lord Himself had spoken. For he had heard Him say, “Whither I go, you cannot come.” Then Jesus made this reply to the said Peter: “Whither I go, you can not follow me now, but you shall follow me afterwards.” Thereupon Peter expressed himself thus: “Lord, why cannot I follow You now? I will lay down my life for Your sake.” And to this presumptuous declaration the Lord responded by predicting his denial. Luke, again, first mentions how the Lord said, “Simon, behold Satan has desired to have you, that he may sift you as wheat; but I have prayed for you, that your faith fail not; and, when you are converted, strengthen your brethren:” next he proceeds immediately to tell us how Peter replied to this effect: “Lord, I am ready to go with You, both unto prison and to death;” and then he continues thus: “And He said, I tell you, Peter, the cock shall not crow this day, before that you shall thrice deny that you know me.” Now, who can fail to perceive that this is an occasion by itself, and that the incident in connection with which Peter was incited to make the presumptuous declaration already referred to is an entirely different one? But, once more, Matthew presents us with the following passage: “And when they had sung an hymn,” he says, “they went out into the Mount of Olives. Then says Jesus unto them, All you shall be offended because of me this night: for it is written, I will smite the shepherd, and the sheep of the flock shall be scattered abroad. But after I am risen again, I will go before you into Galilee.” The same passage is given in precisely the same form by Mark. What similarity is there, however, in these words, or in the ideas expressed by them, either to the terms in which John represents Peter to have made his presumptuous declaration, or to those in which Luke exhibits him as uttering such an asseveration? And so we find that in Matthew's narrative the connection proceeds immediately thus: “Peter answered and said unto Him, Though all men shall be offended because of You, yet will I never be offended. Jesus says unto him, Verily, I say unto you, that this night, before the cock crow, you shall deny me thrice. Peter says unto him, Though I should die with You, yet will I not deny You. Likewise also said all His disciples.”
Source: The Harmony of the Gospels (New Advent)