Why were there poor Jews in Jerusalem in the early church?
The poor Jews in Jerusalem had sold all their property, and the common fund they shared ran out after about twenty years, leaving them destitute. That is why the apostles asked Paul and Barnabas to remember the poor.
Les explains that in the Jerusalem agreement, the leaders gave Paul and Barnabas the right hand of fellowship. Paul and Barnabas would go to the Gentiles, while Peter, James, John, and the others would stay with the circumcision, the Jews. The leaders added one string: that they should remember the poor. Les notes there were a bunch of poor Jews in Jerusalem who had sold all their property, and the common fund had run out after 20 years, leaving them destitute. But God would not abandon them, and He guided the Gentiles to remember them.
But now I go unto Jerusalem to minister unto the saints.