Matthew
Matthew 26:73ESV·traditional attribution

After a little while the bystanders came up and said to Peter, “Certainly you too are one of them, for your accent betrays you.”

John Gill Reformed Baptist @doctorgill

Then began he to curse, and to swear,.... He swore before, and now he began "to curse"; not Christ, as Saul compelled some to blaspheme him, who professed him, and as the Jews formerly cursed Christ, and his followers, in their synagogues: for Peter's crime was bad enough, it need not be made worse than it was: he could never call Jesus accursed; in so...

Albert Barnes Presbyterian @notesbybarnes

Verse 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, . 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.