5 “Now no one of those at the table knew for what intent He spoke this unto him. For some of them thought, because Judas had the money-bag, that Jesus said unto him, Buy those things which we have need of against the feast; or, that he should give something to the poor.” The Lord, therefore, had also a money-box, where He kept the offerings of believers, and distributed to the necessities of His own, and to others who were in need. It was then that the custom of having church-money was first introduced, so that thereby we might understand that His precept about taking no thought for the morrow was not a command that no money should be kept by His saints, but that God should not be served for any such end, and that the doing of what is right should not be held in abeyance through the fear of want. For the apostle also has this foresight for the future, when he says: “If any believer has widows, let him give them enough, that the church may not be burdened, that it may have enough for them that are widows indeed.”
Source: Tractates on the Gospel of John (New Advent)