Peter denied it.”
ὁ δὲ πάλιν ἠρνεῖτο.
This is similar to Matthew, chapter 26:72, Luke, chapter 22:58, and John, chapter 18:25, with some minor changes. All 4 gospels have this 2nd denial of Peter. Mark said that again Peter denied (ὁ δὲ πάλιν ἠρνεῖτο) that he was one of the followers of Jesus. In Matthew there was an oath with this denial. Peter, the great defender of Jesus, again denied him in public for a 2nd time, something he said that he would never do. Be careful what you say.