Matthew 26:70-74

But he denied it before them all, saying, “I do not know what you are talking about.” And when he had gone out to the gateway, another servant-girl saw him and she said to the bystanders, “This man was with Jesus the Nazarene.” And again he denied it with an oath, “I do not know the man.” After a little while the bystanders came up and said to Peter, “Surely you are one of them too; for even your [Galilean] accent gives you away.” Then he began to curse [that is, to invoke God’s judgment on himself] and swear [an oath], “I do not know the man!” And at that moment a rooster crowed.