Peter withdrew to the gateway leading from the street into the courtyard, perhaps because that area was darker and there were fewer people there. There another girl pointed him out to others standing about as one who had been with Jesus "of Nazareth," another derogatory slur in view of the bad reputation of Nazareth (cf. Matthew 2:23). Peter denied her accusation, this time with an oath. Matthew did not mean that Peter used profanity, but he invoked a curse on himself if he was lying. He appealed to something sacred to confirm his truthfulness (cf. Matthew 5:33-34; Matthew 23:16-22). [source][source][source]