Acts 15:37

And Barnabas determined to take with them John, whose surname was Mark.

And Barnabas determined - rather 'counseled,' or 'was minded.' [The received reading, ebouleusato (G1014), is rightly preferred by Tischendorf, though on less manuscript authority than ebouleto (G1011) - volebat-which Lachmann adopts, but which seems a correction, to suit the supposed sense].

To take with them John, whose surname was Mark. They were uncle and nephew, as we learn from Colossians 4:10.