Revelation 1:9

I John,— The apostle, in this and the subsequent verses, mentions the place where the Revelation was given, and describes the manner and circumstances of the first vision: the place was Patmos. Ecclesiastical history tells us, that St. John was here employed in digging in a mine, being banished hither by Domitian the emperor, after he had come unhurt out of a cauldron of boiling oil; but the historical evidence produced for this latter event is very uncertain. Bishop Newton is of opinion, that St. John was banished by Nero.