His name stands first on the list of prophets and teachers of the church at Antioch (Acts 13:1). Luke speaks of him as a "good man" (11:24). He was born of Jewish parents of the tribe of Levi. He was a native of Cyprus, where he had a possession of land (Acts 4:36, 37), which he sold. His personal appearance is supposed to have been dignified and commanding (Acts 14:11, 12). When Paul returned to Jerusalem after his conversion, Barnabas took him and introduced him to the apostles (9:27). They had probably been companions as students in the school of Gamaliel.
The prosperity of the church at Antioch led the apostles and brethren at Jerusalem to send Barnabas there to superintend the movement. He found the work so extensive and weighty that he went to Tarsus in search of Paul to assist him. Paul returned with him to Antioch and laboured with him for a whole year (Acts 11:25, 26). The two were at the end of this period sent up to Jerusalem with the contributions the church at Antioch had made for the poorer brethren there (11:28-30).
Shortly after they returned, bringing John Mark with them, they were appointed as missionaries to Asia Minor, and in this capacity visited Cyprus and some of the principal cities of Asia Minor (Acts 13:14). Returning from this first missionary journey to Antioch, they were again sent up to Jerusalem to consult with the church there regarding the relation of Gentiles to the church (Acts 15:2: Gal. 2:1). This matter having been settled, they returned again to Antioch, bringing the decree of the council as the rule by which Gentiles were to be admitted into the church.
When about to set forth on a second missionary journey, a dispute arose between Paul and Barnabas as to the propriety of taking John Mark with them again. The dispute ended by Paul and Barnabas taking separate routes. Paul took Silas as his companion, and journeyed through Syria and Cilicia; while Barnabas took his nephew John Mark, and visited Cyprus (Acts 15:36-41). Barnabas is not again mentioned by Luke in the Acts.
Initial text from Easton's Bible Dictionary, 1897 -- Please update as needed
Text to integrate from Schaff-Herzog Encyclopedia of Religion:
BARNABAS: The companion of the Apostle Paul, himself called an apostle in Acts xiv, 4, 14. According to Acts iv, 36, he was a Levite born in Cyprus, his original name was Joses, and he was surnamed by the apostles (in Aramaic) Barnebhuah, which is explained by the Greek huios parakleseos ("son of exhortation," not " of consolation," cf. Acts xi, 23) and denotes a prophet in the primitive Christian sense of the word (cf. Acts xiii, 1; xv, 32). Like his aunt, the mother of John Mark (Col. iv, 10), Barnabas seems to have been living in Jerusalem, and he sold his property, after having joined the Christian congregation in the first year of its foundation, for the benefit of needy coreligionists (Acts iv, 37; xii, 12). He soon occupied a leading place in the community.
Of his activity the Book of Acts records that he introduced the still distrusted Saul to the Jerusalem church after his return from Damascus (ix, 27). When the news of the spread of Christianity to Antioch came to Jerusalem Barnabas was sent to the former city (xi, 22-24). From Antioch he went to Tarsus to meet Paul and with him worked for an entire year in the Antioch church (xi, 23-26). Both were sent to Jerusalem with a contribution for the Christians of Judea (44 A.D.) and returned to Antioch with John Mark (xi, 27-30; xii, 25). The three were sent on a missionary journey to Cyprus, Pamphylia, Pisidia, and Lycaonia (xiii, 1 sqq.). In the narrative of this journey Paul occupies the first place from the point where the name " Paul " is substituted for " Saul " (xiii, 9). Instead of " Barnabas and Saul " as heretofore (xi, 30; xii, 25; xiii, 2, 7) " Paul and Barnabas " is now read (xiii, 43, 46, 50; xiv, 20; xv, 2, 22, 35); only in xiv, 14 and xv, 12, 25 does Barnabas again occupy the first place, in the first passage with recollection of xiv, 12, in the last two, because Barnabas stood in closer relation to the Jerusalem church than Paul. Paul appears as the preaching missionary (xiii, 16; xiv, 8-9, 19-20), whence the Lystrans regarded him as Hermes, Barnabas as Zeus (xiv, 12). After this journey follows a long stay in Antioch (xiv, 26-28) until they became involved in a controversy with the Judaizers and were sent to the Apostolic Council at Jerusalem, where the matter was settled (xv, 1-29; Gal. ii, 1-10; see APOSTOLIC COUNCIL AT JERUSALEM). According to Gal. ii, 9-10 Barnabas was included with Paul in the agreement made between them, on the one hand, and James, Peter, and John, on the other, that the two former should in the future preach to the heathen, not forgetting the poor at Jerusalem. Having returned to Antioch and spent some time there (xv, 35), Paul asked Barnabas to accompany him on another journey (xv, 36). Barnabas wished to take John Mark along, but Paul did not, as he had left them on the former journey (xv, 37-38). An unhappy dissension separated the two apostles; Barnabas went with Mark to Cyprus (xv, 39) and is not again mentioned in the Acts; but from Gal. ii, 13 a little more is learned about him, and his weakness under the taunts of the Judaizers is evident; and from I Cor. ix, 6 it may be gathered that he continued to labor as missionary.
Legends begin where authentic history ends. Barnabas is brought to Rome and Alexandria. The " Clementine Recognitions " (i, 7) make him preach in Rome during Christ's lifetime, and Clement of Alexandria (Stromata, ii, 20) makes him one of the seventy disciples. Not older than the third century is the tradition of the later activity and martyrdom of Barnabas in Cyprus, where his remains are said to have been discovered under the emperor Zeno (474-491). The Cyprian church claimed Barnabas as its founder in order to rid itself of the supremacy of the Antiochian bishop, just as did the Milan church afterward, to become more independent of Rome. In this connection, the question whether Barnabas was an apostle became important, and was often treated during the Middle Ages (cf. C. J. Hefele, Das Sendschreiben des Apostels Barnabas, Tubingen, 1840; O. Braunsberger, Der Apostel Barnabas, Mainz, 1876). The statements as to the year of Barnabas's death are discrepant and untrustworthy.
Tertullian and other Western writers regard Barnabas as the author of the Epistle to the Hebrews. This may have been the Roman tradition-- which Tertullian usually follows-- and in Rome the epistle may have had its first readers. But the tradition has weighty considerations against it. According to Photius (Quaest. in Amphil., 123), Barnabas wrote the Book of Acts, and a gospel is ascribed to him (cf. T. Zahn, Geschichte des neutestamentlichen Kanons, ii, 292, Leipsic, 1890). Of more interest is the tradition which makes Barnabas author of an epistle in twenty-one chapters, contained complete in the Codex Sinaiticus at the end of the New Testament. A complete Greek manuscript was discovered by Bryennios at Constantinople, and Hilgenfeld used it for his edition in 1877. Besides this there is a very old Latin version (now in the imperial library at St. Petersburg), in which, however, chaps. xviii-xxi are wanting. Toward the end of the second century the epistle was in great esteem in Alexandria, as the citations of Clement of Alexandria prove. It is also appealed to by Origen. Eusebius, however, objected to it and ultimately the epistle disappeared from the appendix to the New Testament, or rather the appendix disappeared with the epistle. In the West the epistle never enjoyed canonical authority (though it stands beside the epistle of James in the Latin manuscripts). The first editor of the epistle, Menardus (1645) advocated its genuineness, but the opinion to-day is, that Barnabas was not the author. It was probably written in Alexandria in 130-131, and addressed to Christian Gentiles. The author, who formerly labored in the congregation to which he writes, intends to impart to his readers the perfect gnosis that they may perceive that the Christians are the only true covenant people, and that the Jewish people had never been in a covenant with God. His polemics are, above all, directed against Judaizing Christians. In no other writing of that early time is the separation of the Gentile Christians from the patriotic Jews so clearly brought out. The Old Testament, he maintains, belongs only to the Christians. Circumcision and the whole Old Testament sacrificial and ceremonial institution are the devil's work. According to the author's conception, the Old Testament, rightly understood, contains no such injunctions. He is a thorough anti-Judaist, but by no means an antinomist. The main idea is Pauline, and the apostle's doctrine of atonement is more faithfully reproduced in this epistle than in any other postapostolic writing. The author no doubt had read Paul's epistles; he has a good knowledge of gospel-history but which of the gospels, if any, he had read, can not be asserted. He quotes IV Esdras (xii, 1) and Enoch (iv, 3; xvi, 5). The closing section (chaps. xviii-xxi), which contains a series of moral injunctions, is only loosely connected with the body of the epistle, and its true relation to the latter has given rise to much discussion.