The writing of 1 Corinthians came partly as a response to a letter that the Corinthian church had sent to Paul (1 Corinthians 7:1). That letter had contained a number of enquiries, and the phrase now concerning
indicates that Paul is about to respond to one of these (see also 1 Corinthians 7:1, 1 Corinthians 7:25; 1 Corinthians 8:1; 1 Corinthians 12:1). This specific enquiry is related to the collection for the saints.
From other places in the New Testament we know that the collection for the saints
was a large collection in aid of the impoverished Jewish believers who were living in Jerusalem (Romans 15:25–28; 2 Corinthians 8:1 – 9:15; Galatians 2:1–10). Paul directed churches everywhere to participate in it. That he had discussed the matter with the Corinthians before is evident from the general way in which he now refers to it.
After persecution broke out in Jerusalem, many believers fled to other places and many who remained fell into poverty (Acts 8:1; Acts 11:28–29). Paul was eager to help these believers (Acts 11:30; Galatians 2:9–10). He reminded the Gentile churches that they were indebted to the church in Jerusalem, since it was from that church that all their spiritual blessings
had come (Romans 15:26–27).
Participation in the collection was not a matter of choice. When Paul writes that he has directed
the churches, he uses a verb that was often used for military commands. Added to that, the Greek word for collection
refers to a compulsory collection, as of taxes.
1 Now concerning the collection for the saints: as I directed the churches of Galatia, so you also are to do.