Albert Barnes on Matthew 26:73

And after a while. That is, about an hour after, (Luke.) Peter, by this time, had returned into the palace or hall, and stood warming himself by the fire, Jn 18:25.

Thy speech betrayeth thee. Your language makes it manifest that you are of his company. That is, as Mark adds, he was a Galilean; and in this way his speech betrayed him. It is probable that the Galileans were distinguished for some peculiarity of pronunciation, perhaps some peculiar rusticity or coarseness in their manner of speaking, that distinguished them from the refinement of the capital, Jerusalem. This charge, John says, Jn 18:26 was supported by the express affirmation of a kinsman of Malchus, the servant of the high priest, that he had seen him in the garden.