31 For if they be urged from the Gospel that they should put nothing by for the morrow, they most rightly answer, Why then had the Lord Himself a bag in which to put by the money which was collected? Why so long time beforehand, on occasion of impending famine, were supplies of grain sent to the holy fathers? Why did Apostles in such wise provide things necessary for the indigence of saints lest there should be lack thereafter, that most blessed Paul should thus write to the Corinthians in his Epistle: “Now concerning the collection for the saints, as I have given order to the Churches of Galatia, even so do ye.
Upon the first day of the week let every one of you lay by him in store, as God has prospered him, that the gatherings be not then first made when I come. And when I come, whomsoever you shall approve by your letters, them will I send to bring your liberality unto Jerusalem. And if it be meet that I go also, they shall go with me?” These and much else they most copiously and most truly bring forward. To whom we answer: You see then, albeit the Lord said, “Take no thought for the morrow,” yet you are not by these words constrained to reserve nothing for the morrow: then why do ye say that by the same words you are constrained to do nothing? Why are the birds of the air not a pattern unto you for reserving nothing, and you will have them to be a pattern for working nothing?
Source: On the Work of Monks (New Advent)