1 Corinthians 9:5

Evidently it was customary for the other apostles and the Lord’s physical brothers to take their wives with them when they traveled to minister. The churches they served covered the expenses of these women as well as those of their husbands. Paul may have mentioned Peter in particular because he had a strong following in Corinth (1 Corinthians 1:12). His references to the Lord’s brothers in this verse and to Barnabas in the next do not necessarily mean that these men had visited Corinth. Perhaps the Corinthians knew about their habits of ministering second-hand.