12 If, therefore, you know any zealous for the glory of God, and at the same time disposed and fit to go on these holy expeditions, encourage them, so that, the will of God being well known and clear, they may listen not to flesh and blood, but rather hasten to correspond to the call of the Holy Spirit. But from the remaining priests, from the Religious Orders of both sexes from all the faithful, in short, entrusted to your care, required with all urgency, that by their unremitting prayers they obtain the Divine assistance for those who sow the seed of the Word of God. And let them employ as intercessors the Virgin Mother of God, who has power to destroy all the monsters of error, and her most chaste Spouse, whom many missions have already taken as their patron and protector, and whom the Apostolic See has recently given as Patron to the Universal Church. Let them invoke the Princes of the Apostles and the whole of that company from whom the first preaching of the Gospel resounded throughout the whole world; and in short all the others eminent for sanctity, who have spent their strength in the same ministry and poured forth their life together with their blood. Let almsgiving be added to prayer, for its efficacy is such that it will render those who are widely separated in place and distracted with other cares coadjutors of Apostolic men, and will make them their companions both in labour and merit. The times, indeed, are such that many persons suffer from want at home; but let no one despond on that account, for the amount required for this purpose can scarcely be a heavy contribution for any one, although from many small sums added together tolerably large supplies can be raised. But when you, Venerable Brethren, are engaged in exhortation, let every one consider that his liberality will not be to him a loss, but a gain, because he that giveth to the poor lendeth to the Lord, and on that account the practice of almsgiving has been called the most profitable of all practices. Certainly if, according to the testimony of Jesus Christ, a cup of cold water given to one of these little ones will not lose its reward, the most ample reward will await him who shall have spent even a small sum of money upon sacred missions, and, adding also his prayers, exercises at the same time many and various offices of charity, and, doing that which the holy Fathers have said is the most divine of all divine works, becomes a helper of God Himself for the salvation of his neighbours.
Source: Sancta Dei Civitas (Vatican.va)