4:19 Prisca and Aquila. “Prisca” is a shortened form of “Priscilla,” as it is spelled elsewhere in Acts and Paul’s letters. She and her husband Aquila had been friends of Paul from the time he first visited Corinth on his second missionary journey. They were Jews, and like Paul were tentmakers (Acts 18:2, 3). They had come to Corinth from Rome. Later they accompanied Paul to Ephesus (Acts 18:18, 19) and hosted a house church there for several years before returning to Rome (Rom. 16:3, 4; 1 Cor. 16:19). They had now apparently returned to Ephesus where Timothy was (1 Tim. 1:3).
the household of Onesiphorus. See note 1:16. This greeting indicates that Timothy was still in Ephesus (1:18).