"Nearby a cock crowed and I thought, 'That is for betrayal, but who is the traitor?'"

During the Last Supper, Jesus foretold that Peter would deny him three times before the cock crowed (before the cock crowed twice according to Mark 14). Faced with a hostile crowd after Jesus's arrest, Peter did as prophesied.

The cock crows three times in Wide Sargasso Sea, echoing Peter's three denials of Christ.