Matthew 26:72

And again he denied with an oath, I know not the man. And after a little while, they that stood by came and said to Peter, Of a truth thou also art one of them; for thy speech maketh thee known.

How vain was Peter's thought that he might remain unknown, unchallenged, or unnoticed by that vicious company gathered around the Lord. Try as he might have done to appear as one of them, even engaging in conversation, one fatal flaw in the plan exposed him, and that was his speech. The accent of a Galilean fisherman would have been instantly noticed in such a group as that, and of course that is exactly what happened.

I know not the man! How sadly do those words burn upon the sacred page. He who had first confessed Christ as the "Son of God" had at that point so far defected as to deny that he was even acquainted with Jesus and to reinforce the denial with an oath.