"15 Simon Peter followed Jesus, and so did another disciple. Since that disciple was known to the high priest, he entered with Jesus into the court of the high priest, 16 but Peter stood outside at the door. So the other disciple, who was known to the high priest, went out and spoke to the servant girl who kept watch at the door, and brought Peter in. 17 The servant girl at the door said to Peter, “You also are not one of this man's disciples, are you?” He said, “I am not.” 18 Now the servants and officers had made a charcoal fire, because it was cold, and they were standing and warming themselves. Peter also was with them, standing and warming himself.
19 The high priest then questioned Jesus about his disciples and his teaching. 20 Jesus answered him, “I have spoken openly to the world. I have always taught in synagogues and in the temple, where all Jews come together. I have said nothing in secret. 21 Why do you ask me? Ask those who have heard me what I said to them; they know what I said.” 22 When he had said these things, one of the officers standing by struck Jesus with his hand, saying, “Is that how you answer the high priest?” 23 Jesus answered him, “If what I said is wrong, bear witness about the wrong; but if what I said is right, why do you strike me?” 24 Annas then sent him bound to Caiaphas the high priest.
25 Now Simon Peter was standing and warming himself. So they said to him, “You also are not one of his disciples, are you?” He denied it and said, “I am not.” 26 One of the servants of the high priest, a relative of the man whose ear Peter had cut off, asked, “Did I not see you in the garden with him?” 27 Peter again denied it, and at once a cock crowed."
John 18:15-27
What are we to say, then, of Luke 22:31, and Christ's intercession for Peter? Did it fail then for Peter? No; Christ did not say that Peter would not fall. Indeed, the way that Christ preserved Peter's faith was to allow him to fall here, because he had to be brought to an end of himself. When Christ really takes us in hand, we need to watch out there is something very firm - even ruthless - about His tender dealing with us. And, as P.T. Forsyth once said, He is strong enough to resist pity till sorrow and shame and penitence have done their gracious work in us. It was down there, in that abject place of moral failure and collapse, that Peter learned the truth about himself at last, and that the foundations for the new Peter were laid, Peter the rock, the man of the cross. His faith did not fail, only his faith in himself; his faith was purged and purified and reborn, as it were, and emerged a new thing. But we must think also of the sequel, to anticipate the last chapter of John's gospel. In the highly dramatic encounter on the shores of the lake, it becomes clear that it was not Peter's faith, but his love, that was called in question. The lesson this teaches us is that if we love, we shall be faithful. To love means to be loyal, even to our own hurt. It is the personal relationship that matters, and is indeed paramount.