15 Simon Peter followed Jesus, as did another of the disciples. That other disciple was acquainted with the high priest, so he was allowed to enter the high priest's courtyard with Jesus. 16 Peter had to stay outside the gate. Then the disciple who knew the high priest spoke to the woman watching at the gate, and she let Peter in. 17 The woman asked Peter, "You're not one of that man's disciples, are you?" "No," he said, "I am not." 18 Because it was cold, the household servants and the guards had made a charcoal fire. They stood around it, warming themselves, and Peter stood with them, warming himself.
19 Inside, the high priest began asking Jesus about his followers and what he had been teaching them. 20 Jesus replied, "Everyone knows what I teach. I have preached regularly in the synagogues and the Temple, where the people gather. I have not spoken in secret. 21 Why are you asking me this question? Ask those who heard me. They know what I said." 22 Then one of the Temple guards standing nearby slapped Jesus across the face. "Is that the way to answer the high priest?" he demanded. 23 Jesus replied, "If I said anything wrong, you must prove it. But if I'm speaking the truth, why are you beating me?" 24 Then Annas bound Jesus and sent him to Caiaphas, the high priest.
25 Meanwhile, as Simon Peter was standing by the fire warming himself, they asked him again, "You're not one of his disciples, are you?" He denied it, saying, "No, I am not." 26 But one of the household slaves of the high priest, a relative of the man whose ear Peter had cut off, asked, "Didn't I see you out there in the olive grove with Jesus?" 27 Again Peter denied it. And immediately a rooster crowed.
Matthew Henry's Commentary on John 18:15-27
Commentary on John 18:13-27
(Read John 18:13-27)
Simon Peter denied his Master. The particulars have been noticed in the remarks on the other Gospels. The beginning of sin is as the letting forth of water. The sin of lying is a fruitful sin; one lie needs another to support it, and that another. If a call to expose ourselves to danger be clear, we may hope God will enable us to honour him; if it be not, we may fear that God will leave us to shame ourselves. They said nothing concerning the miracles of Jesus, by which he had done so much good, and which proved his doctrine. Thus the enemies of Christ, whilst they quarrel with his truth, wilfully shut their eyes against it. He appeals to those who heard him. The doctrine of Christ may safely appeal to all that know it, and those who judge in truth bear witness to it. Our resentment of injuries must never be passionate. He reasoned with the man that did him the injury, and so may we.