And the contention was so sharp - The word used here παροξυσμός paroxusmos is that from which our word "paroxysm" is derived. It may denote "any excitement of mind," and is used in a good sense in Hebrews 10:24. It here means, however, "a violent altercation" that resulted in their separation for a time, and in their engaging in different spheres of labor.
And sailed into Cyprus - This was the native place of Barnabas. See the notes on Acts 4:36.

The contention was so sharp between them - For all this sentence, there is only in the Greek text εγενετο ουν παροξυσμος; there was therefore a paroxysm, an incitement, a stirring up, from παροξυνω, compounded of παρα, intensive, and οξυνω, to whet, or sharpen: there was a sharp contention. But does this imply anger or ill-will on either side? Certainly not. Here, these two apostles differed, and were strenuous, each in support of the part he had adopted. "Paul," as an ancient Greek commentator has it, "being influenced only with the love of righteousness; Barnabas being actuated by love to his relative." John Mark had been tried in trying circumstances, and he failed; Paul, therefore, would not trust him again. The affection of Barnabas led him to hope the best, and was therefore desirous to give him another trial. Barnabas would not give up: Paul would not agree. They therefore agreed to depart from each other, and take different parts of the work: each had an attendant and companion at hand; so Barnabas took John Mark, and sailed to Cyprus: Paul took Silas, and went into Syria. John Mark proved faithful to his uncle Barnabas; and Silas proved faithful to his master Paul. To all human appearance it was best that they separated; as the Churches were more speedily visited, and the work of God more widely and more rapidly spread. And why is it that most men attach blame to this difference between Paul and Barnabas? And why is it that this is brought in as a proof of the sinful imperfection of these holy apostles? Because those who thus treat the subject can never differ with another without feeling wrong tempers; and then, as destitute of good breeding as they are of humility, they attribute to others the angry, proud, and wrathful dispositions which they feel in themselves; and, because they cannot be angry and sin not, they suppose that even apostles themselves cannot. Thus, in fact, we are always bringing our own moral or immoral qualifications to be a standard, by which we are to judge of the characters and moral feelings of men who were actuated by zeal for God's glory, brotherly kindness, and charity. Should any man say there was sin in this contention between Paul and Barnabas, I answer, there is no evidence of this in the text. Should he say, the word παροξυσμος, paroxysm, denotes this, I answer, it does not. And the verb παροξυνομαι is often used in a good sense. So Isocrates ad Demosth. cap. xx. μαλιϚα δ' αν παροξυνθειης ορεχθηναι των καλων εργων· "But thou wilt be the more stirred up to the love of good works." And such persons forget that this is the very form used by the apostle himself, Hebrews 10:24 : και κατανοωμεν αλληλους εις παροξυσμον αγαπης και καλων εργων· which, these objectors would be highly displeased with me, were I to translate, Let us consider one another to an angry contention of love and good works. From these examples, it appears that the word is used to signify incitement of any kind; and, if taken in a medical sense, to express the burning fit of an ague: it is also taken to express a strong excitement to the love of God and man, and to the fruits by which such love can be best proved; and, in the case before us, there was certainly nothing contrary to this pure principle in either of those heavenly men. See also Kypke on Hebrews 10:24.

(16) And (r) the contention was so sharp between them, that they departed asunder one from the other: and so Barnabas took Mark, and sailed unto Cyprus;
(16) God uses the faults of his servants to the profit and building of the Church: yet we have to take heed, even in the best matters, that we do not let our anger overflow.
(r) They were in great heat: but in this we have to consider the power of God's counsel, for by this means it came to pass that the doctrine of the Gospel was spread into many places.

And the contention was so sharp between them,.... About this matter; Barnabas insisting on it, that John Mark should go with them, he being a relation of his; and in whose favour it might be urged, that his mother Mary was an excellent good woman, who had received the saints into her house, in a time of persecution; and that it should be considered, that this her son was but a young man, and could not be thought to have that courage, resolution, constancy, and solidity, as older professors and ministers; and that his crime was not very heinous, and should be overlooked. Paul, on the other hand, opposing his going with them, as a very unworthy person, because he had behaved so cowardly, and had shown such a coldness and indifference to the work of the ministry, and had so shamefully left them; and thus they disputed the point till there was a paroxysm between them, as is the word used: they were irritated and provoked by one another, and were so warmed and heated on both sides,
that they departed asunder one from another; thus as soon almost as peace was made in the church, a difference arises among the ministers of the word, who are men of like passions with others; and though it is not easy to say which was to blame most in this contention; perhaps there were faults on both sides, for the best men are not without their failings; yet this affair was overruled by the providence of God, for the spread of his Gospel, and the enlargement of his interest; for when these two great and good men parted from one another, they went to different places, preaching the word of God:
and so Barnabas took Mark and sailed unto Cyprus;
See Gill on Acts 13:4.

And the contention was so sharp between them--such was the "irritation," or "exacerbation."
that they departed asunder one from the other--Said they not truly to the Lystrians that they were "men of like passions with them"; (Acts 14:15). But who was to blame? (1) That John Mark had either tired of the work or shrunk from the dangers and fatigues that yet lay before them, was undeniable; and Paul concluded that what he had done he might, and probably would, do again. Was he wrong in this? (See Proverbs 25:19). But (2) To this Barnabas might reply that no rule was without exception; that one failure, in a young Christian, was not enough to condemn him for life; that if near relationship might be thought to warp his judgment, it also gave him opportunities of knowing the man better than others; and that as he was himself anxious to be allowed another trial (and the result makes this next to certain), in order that he might wipe out the effect of his former failure and show what "hardness he could now endure as a good soldier of Jesus Christ," his petition ought not to be rejected. Now, since John Mark did retrieve his character in these respects, and a reconciliation took place between Paul and him, so cordial that the apostle expresses more than once the confidence he had in him and the value he set upon his services (Colossians 4:10-11; 2-Timothy 4:11), it may seem that events showed Barnabas to be in the right, and Paul too harsh and hasty in his judgment. But, in behalf of Paul, it may well be answered, that not being able to see into the future he had only the unfavorable past to judge by; that the gentleness of Barnabas (Acts 4:36; Acts 11:24) had already laid him open to imposition (see on Galatians 2:13), to which near relationship would in this case make him more liable; and that in refusing to take John Mark on this missionary journey he was not judging his Christian character nor pronouncing on his fitness for future service, but merely providing in the meantime against being again put to serious inconvenience and having their hands weakened by a possible second desertion. On the whole, then, it seems clear that each of these great servants of--Christ had something to say for himself, in defense of the position which they respectively took up; that while Barnabas was quite able to appreciate the grounds on which Paul proceeded, Paul was not so competent to judge of the considerations which Barnabas probably urged; that while Paul had but one object in view, to see that the companion of their arduous work was one of thoroughly congenial spirit and sufficient nerve, Barnabas, over and above the same desire, might not unreasonably be afraid for the soul of his nephew, lest the refusal to allow him to accompany them on their journey might injure his Christian character and deprive the Church of a true servant of Jesus Christ; and that while both sought only the glory of their common Master, each looked at the question at issue, to some extent, through the medium of his own temperament, which grace sanctifies and refines, but does not destroy--Paul, through the medium of absolute devotion to the cause and kingdom of Christ, which, warm and womanly as his affections were, gave a tinge of lofty sternness to his resolves where that seemed to be affected; Barnabas, through the medium of the same singleness of heart in Christ's service, though probably not in equal strength (Galatians 2:13), but also of a certain natural gentleness which, where a Christian relative was concerned, led him to attach more weight to what seemed for his spiritual good than Paul could be supposed to do. In these circumstances, it seems quite possible that they might have amicably "agreed to differ," each taking his own companion, as they actually did. But the "paroxysm" (as the word is), the "exacerbation" which is expressly given as the cause of their parting, shows but too plainly, that human infirmity amidst the great labors of the Church at Antioch at length sundered those who had sweetly and lovingly borne together the heat and burden of the day during a protracted tour in the service of Christ. "Therefore let no man glory in men" (1-Corinthians 3:21). As for John Mark, although through his uncle's warm advocacy of his cause he was put in a condition to dissipate the cloud that hung over him, how bitter to him must have ever afterwards been the reflection that it was his culpable conduct which gave occasion to whatever was sinful in the strife between Paul and Barnabas, and to a separation in action, though no doubt with a mutual Christian regard, between those who had till then wrought nobly together! How watchful does all this teach Christians, and especially Christian ministers and missionaries, to be against giving way to rash judgment and hot temper towards each other, especially where on both sides the glory of Christ is the ground of difference! How possible is it that in such cases both parties may, on the question at issue, be more or less in the right! How difficult is it even for the most faithful and devoted servants of Christ, differing as they do in their natural temperament even under the commanding influence of grace, to see even important questions precisely in the same light! And if, with every disposition to yield what is unimportant, they still feel it a duty each to stand to his own point, how careful should they be to do it lovingly, each pursuing his own course without disparagement of his Christian brother! And how affectingly does the Lord overrule such difference of judgment and such manifestations of human infirmity, by making them "turn out rather unto the furtherance of the Gospel"; as in this case is eminently seen in the two missionary parties instead of one, not travelling over the same ground and carrying their dispute over all the regions of their former loving labors, but dividing the field between them!
and so Barnabas took Mark, and sailed unto Cyprus; and Paul chose Silas--(See on Acts 15:34) --going two and two, as the Twelve and the Seventy (Mark 6:7; Luke 10:1).

And there was a sharp contention - Literally, a paroxysm, or fit of a fever. But nothing in the text implies that the sharpness was on both sides. It is far more probable that it was not; that St. Paul, who had the right on his side, as he undoubtedly had,) maintained it with love. And Barnabas taking Mark with him, sailed away to Cyprus - Forsaking the work in which he was engaged, he went away to his own country.