John Calvin Commentary Acts 12:25

"And Barnabas and Saul returned from Jerusalem, when they had fulfilled their ministration, taking with them John whose surname was Mark." — Acts 12:25 (ASV)

And Barnabas and Paul. The ministry that Luke says Barnabas and Paul finished must refer to the alms, of which mention was made before. For after Agabus the prophet had foretold the famine and barrenness, the brethren gathered money at Antioch, by which they might relieve the need of the church in Jerusalem; the carrying of this money was committed to Barnabas and Paul. Now Luke says that they returned to Antioch, so that he might move on to a new history. He adds, that they took with them John, whose surname was Mark, whose mother was honorably commended before, to keep them company, who was afterward, as we shall see, a cause of grievous and dangerous discord between them.