The Call To Evangelise Asia Minor (12:25-13:3).
‘And Barnabas and Saul returned from Jerusalem, when they had fulfilled their ministration, taking with them John whose surname was Mark.'
Accepting the text as here (with A and p74) Barnabas and Saul had come to Jerusalem and had ministered to the true people of God the love of the church at Antioch. Having accomplished their task and demonstrated the love and unity between the two churches, they now returned to Antioch, and took with them John Mark, Barnabas' cousin.
However, certain good manuscripts (Aleph & B (a powerful combination) together with P) support the reading ‘returned to Jerusalem'. This can make good sense as indicating that they had been distributing the Antiochene gifts among the elders of Judaea and then returned to Jerusalem, having fulfilled their ministry to them.
It actually makes little difference which we take for they then clearly had to return to Antioch in order that what happened next might follow. If we accept the latter texts then their return is just assumed. However, as they took Mark with them, it suggests that in this rare case the more difficult text is wrong so that it should read ‘from Jerusalem', unless we take it to mean, ‘returned to Jerusalem (and then left there) taking Mark with them', with the words in brackets simply assumed.