Charles Ellicott Commentary Matthew 26:74

"Then began he to curse and to swear, I know not the man. And straightway the cock crew." — Matthew 26:74 (ASV)

To curse and to swear — We may infer from the two words that he used some common formula of execration, such as, for example, God do so to me and more also (1 Kings 19:2; 1 Kings 20:10), as well as the oath-formula, “By Heaven,” or “By the Temple.”

Immediately the cock crew — St. Mark alone records the first cock-crow. The Greek has no article: “a cock crew.” We find from Mark 13:35 that “cock-crowing” had become a familiar phrase, as it is with us, for the earliest hour of dawn.