St. Barnabas, who was originally known as Joseph, a rich levite, was a native of Cyprus. According to the Acts of the Apostles, he, having land, sold it, and brought the price, and laid it at the feet of the apostles.” In the company of St. Paul they journeyed to the cities of Asia Minor and the people were amazed at their preaching. St. Paul constantly gives him the title apostle, which, has therefore been ascribed to him in the Liturgy. Persecuted by the Jews he was stoned to death in the Island of Cyprus. His name is mentioned in the Canon of the Mass immediately after that of St. Matthias.
(Source: The New Roman Missal by Father Lasance).