36 Some time later Paul said to Barnabas, "Let us go back and visit the believers in every town where we preached the word of the Lord, and let us find out how they are getting along."
37 Barnabas wanted to take John Mark with them,
38 but Paul did not think it was right to take him, because he had not stayed with them to the end of their mission, but had turned back and left them in Pamphylia. 1

References for Acts 15:38

39 There was a sharp argument, and they separated: Barnabas took Mark and sailed off for Cyprus,