 Paul, in his missionary travels, he was collecting an offering for the church in Jerusalem. Now, this was about the mid-50s when he writes to the Corinthians, and he mentions this offering in a few of the other letters that he wrote around the same time, including Romans and 1 Corinthians. So he's reminding the Corinthian Christians about something they've already talked about. We don't know exactly how, but somehow the Christians in Jerusalem, they fell into great poverty.