New Defender's Study Bible Notes
12:25 returned from Jerusalem. Barnabas and Saul had been sent to Jerusalem by the church at Antioch, bringing material aid to the Christians there during the hard times occasioned by the recent famine (Acts 11:27-30). Whether they were with the believers praying for Peter in Mark’s home is not stated, but it is there they must have counseled with Mark and decided to take him back to Antioch with them.
12:25 John. John Mark was a nephew of Barnabas (although some say he was a cousin—Colossians 4:10) and evidently a close friend of Peter (the early church fathers said much of what Mark wrote in his gospel was obtained from Peter). He probably was a Levite, like his uncle (Acts 4:36) and thus well instructed in the Scriptures, as well as from a prosperous family.