From there he went to Tarsus, to seek Paul, and came with him to Antioch. In the church of that city they remained for a year, and they gave the commandments of the Christian faith and life to those men. It was here also that it happened the worshippers of Jesus Christ were first called Christians. And the disciples of Paul and Barnabas through their own means supported the Christians who were in Judea, sending the money there by Paul and Barnabas. Having performed this work of charity, taking with them John, who was surnamed Mark, they returned to Antioch.
And while Paul and Barnabas were ministering to the Lord in the Church of Antioch, fasting and praying with the other prophets and doctors, the Holy Ghost said: Set apart for me Saul and Barnabas unto the work to which I have called them. Then they fasting and praying, and imposing their hands upon them, sent them away. Then they went to Seleucia, and from there to Cyprus; and besides this, they passed through many cities and countries, preaching the Gospel with the greatest profit to their hearers. Finally Barnabas separated from Paul, and together with John, who was surnamed Mark, sailed to Cyprus; and there, about the seventh year of the reign of Nero, on the 11th day of June, he joined the martyr's crown with the dignity of the apostolic office. In the reign of the Emperor Zeno, his body was discovered in the island of Cyprus; on his breast lay the Gospel of Matthew, copied by the hand of Barnabas.
From the Office of St. Barnabas
Commentary of St. John Chrysostom on Mathew 10, 16-22
And now, that they may understand how that this is a new kind of warfare, and an unaccustomed manner of contending, when he sendeth them forth unarmed, providing neither gold, nor silver, nor brass in their purses; nor scrip for their journey, neither two coats, neither shoes, nor yet staves, left to the hospitality of whosoever would receive them, he maketh not here an end to his discourse, but, in manifestation of his unspeakable power, he biddeth them, so going, to shew forth the meekness of sheep, seeing they were about going unto wolves, neither simply unto wolves, but in the very midst of wolves. Neither is it only the meekness of sheep which he biddeth them have, but also the harmlessness of doves, that he might so much the more gloriously display his power, when the sheep overcame the wolves. These are the sheep which albeit they abide in the midst of wolves, and are mangled by many a bite, not only are not destroyed, but do gradually make the wolves change their nature, and become sheep themselves. Beyond all doubt, it is a greater and more marvellous thing to change the minds of enemies, and to turn their thoughts round, than to kill them; more especially when the work is to be done by only twelve sheep, and the whole world is full of the wolves. Shame them upon us, whose deeds are so contrary, and who rather run like wolves upon our enemies. For so long as we are sheep we conquer, yea, though a thousand wolves be gathered round about us, we overcome, and are the conquerors: but if we become wolves ourselves, then are we conquered. For then doth the Shepherd's help forsake us, who feedeth not wolves but sheep.