Mark 14:70-72

But again he denied it. And after a little while again the bystanders said to Peter, “Certainly you are one of them; for you are a Galilean.” But he began to invoke a curse on himself and to swear, “I do not know this man of whom you speak.” And immediately the cock crowed a second time. And Peter remembered how Jesus had said to him, “Before the cock crows twice, you will deny me three times.” And he broke down and wept.