Luke 22:58

‘And after a little while another saw him, and said, “You also are one of them.” But Peter said, “Man, I am not.” '

A short time later a man looked at him and said, “You are one of them.” His panic then grew worse and he said fiercely, “Man, I am not.” How he wished then that he was anywhere but where he was. And yet he was still brave enough to remain there. He probably argued to himself that his reaction had been justified.

(Mark tells us that it was the maid who had again insisted to those who stood by that Peter was a follower of Jesus. Thus this man, who spoke directly to Peter, must clearly have been one who took her up on her words and actually made the accusation to him. Here Luke is following his other source, whether oral or written. In a crowded courtyard, where there was much interest in the subject, any comments would naturally be taken up by others, and she had already challenged him once. In the face of his vehement denial she would hesitate about doing it again.).