5:13 She . . . at Babylon. Probably a reference to the church in Rome (Introduction: Date and Occasion).

Mark, my son. John Mark (Acts 12:12, 25; 13:5, 13; 15:37–39). According to Papias (c. a.d. 60–130), Mark worked closely with Peter and derived much of the information for the Gospel of Mark from the apostle.