John 21 - NKJV Woman's Study Bible

21:18–19 Jesus prophesied that Peter would die as a result of following him. He made a comparison between Peter’s life as a youth and as an old man. Jesus indicated that Peter would die a martyr’s death. “Stretch out your hands” referred to crucifixion. Tradition holds that Peter was crucified upside down in Rome between AD 64 and 68.