9 If you dread and fear, lest, if you begin to act thus abundantly, your patrimony being exhausted with your liberal dealing, you may perchance be reduced to poverty; be of good courage in this respect, be free from care: that cannot be exhausted whence the service of Christ is supplied, whence the heavenly work is celebrated. Neither do I vouch for this on my own authority; but I promise it on the faith of the Holy Scriptures, and on the authority of the divine promise.
The Holy Spirit speaks by Solomon, and says, “He that gives unto the poor shall never lack, but he that turns away his eye shall be in great poverty;” showing that the merciful and those who do good works cannot want, but rather that the sparing and barren hereafter come to want. Moreover, the blessed Apostle Paul, full of the grace of the Lord's inspiration, says: “He that ministers seed to the sower, shall both minister bread for your food, and shall multiply your seed sown, and shall increase the growth of the fruits of your righteousness, that in all things you may be enriched.” And again: “The administration of this service shall not only supply the wants of the saints, but shall be abundant also by many thanksgivings unto God;” because, while thanks are directed to God for our almsgivings and labours, by the prayer of the poor, the wealth of the doer is increased by the retribution of God.
And the Lord in the Gospel, already considering the hearts of men of this kind, and with prescient voice denouncing faithless and unbelieving men, bears witness, and says: “Take no thought, saying, What shall we eat? Or, What shall we drink? Or, Wherewithal shall we be clothed? For these things the Gentiles seek. And your Father knows that you have need of all these things. Seek first the kingdom of God, and His righteousness; and all these things shall be added unto you.” He says that all these things shall be added and given to them who seek the kingdom and righteousness of God. For the Lord says, that when the day of judgment shall come, those who have laboured in His Church are admitted to receive the kingdom.
Source: The Treatises of Cyprian (New Advent)