And some days after Paul said unto Barnabas,
Let us go again and visit our brethren in every city
where we have preached the word of the Lord,
and see how they do.
And Barnabas determined to take with them John,
whose surname was Mark.
But Paul thought not good to take him with them,
who departed from them from Pamphylia,
and went not with them to the work.
And the contention was so sharp between them,
that they departed asunder one from the other:
and so Barnabas took Mark,
and sailed unto Cyprus;
And Paul chose Silas,
and departed, being recommended by the brethren unto the grace of God.
And he went through Syria and Cilicia,
confirming the churches.
Acts 15:36-41
"Both Paul and Barnabas had a tender regard for those who had recently accepted the gospel message under their ministry, and they longed to see them once more. This solicitude Paul never lost. Even when in distant mission fields, far from the scene of his earlier labors, he continued to bear upon his heart the burden of urging these converts to remain faithful,..." Acts of the Apostles p.201 E.G.W.