To defend the weak, or to help strangers, or to perform similar duties, greatly adds to one's worth, especially in the case of tried men. Whilst one gets great blame for love of money; wastefulness, also, in the case of priests is very much condemned.
102. The regard in which one is held is also very much enhanced when one rescues a poor man out of the hands of a powerful one, or saves a condemned criminal from death; so long as it can be done without disturbance, for fear that we might seem to be doing it rather for the sake of showing off than for pity's sake, and so might inflict severer wounds while desiring to heal slighter ones. But if one has freed a man who is crushed down by the resources and faction of a powerful person, rather than overwhelmed by the deserts of his own wickedness, then the witness of a great and high opinion grows strong.
103. Hospitality also serves to recommend many. For it is a kind of open display of kindly feelings: so that the stranger may not want hospitality, but be courteously received, and that the door may be open to him when he comes. It is most seemly in the eyes of the whole world that the stranger should be received with honour; that the charm of hospitality should not fail at our table; that we should meet a guest with ready and free service, and look out for his arrival.
104. This especially was Abraham's praise, for he watched at the door of his tent, that no stranger by any chance might pass by. He carefully kept a lookout, so as to meet the stranger, and anticipate him, and ask him not to pass by, saying: “My lord, if I have found favour in your sight, pass not by your servant.” Therefore as a reward for his hospitality, he received the gift of posterity.
105. Lot also, his nephew, who was near to him not only in relationship but also in virtue, on account of his readiness to show hospitality, turned aside the punishment of Sodom from himself and his family.
106. A man ought therefore to be hospitable, kind, upright, not desirous of what belongs to another, willing to give up some of his own rights if assailed, rather than to take away another's. He ought to avoid disputes, to hate quarrels. He ought to restore unity and the grace of quietness. When a good man gives up any of his own rights, it is not only a sign of liberality, but is also accompanied by great advantages. To start with, it is no small gain to be free from the cost of a lawsuit. Then it also brings in good results, by an increase of friendship, from which many advantages rise. These become afterwards most useful to the man that can despise a little something at the time.
107. In all the duties of hospitality kindly feeling must be shown to all, but greater respect must be given to the upright. For “Whosoever receives a righteous man, in the name of a righteous man, shall receive a righteous man's reward,” as the Lord has said. Such is the favour in which hospitality stands with God, that not even the draught of cold water shall fail of getting a reward. You see that Abraham, in looking for guests, received God Himself to entertain. You see that Lot received the angels. And how do you know that when you receive men, thou dost not receive Christ? Christ may be in the stranger that comes, for Christ is there in the person of the poor, as He Himself says: “I was in prison and you came to Me, I was naked and you clothed Me.”.
108. It is sweet, then, to seek not for money but for grace. It is true that this evil has long ago entered into human hearts, so that money stands in the place of honour, and the minds of men are filled with admiration for wealth. Thus love of money sinks in and as it were dries up every kindly duty; so that men consider everything a loss which is spent beyond the usual amount. But even here the holy Scriptures have been on the watch against love of money, that it might prove no cause of hindrance, saying: “Better is hospitality, even though it consists only of herbs.” And again: “Better is bread in pleasantness with peace.” For the Scriptures teach us not to be wasteful, but liberal.
109. There are two kinds of free-giving, one arising from liberality, the other from wasteful extravagance. It is a mark of liberality to receive the stranger, to clothe the naked, to redeem the captives, to help the needy. It is wasteful to spend money on expensive banquets and much wine. Wherefore one reads: “Wine is wasteful, drunkenness is abusive.” It is wasteful to spend one's own wealth merely for the sake of gaining the favour of the people. This they do who spend their inheritance on the games of the circus, or on theatrical pieces and gladiatorial shows, or even a combat of wild beasts, just to surpass the fame of their forefathers for these things. All this that they do is but foolish, for it is not right to be extravagant in spending money even on good works.
110. It is a right kind of liberality to keep due measure towards the poor themselves, that one may have enough for more; and not to go beyond the right limit for the sake of winning favour. Whatever comes forth out of a pure sincere disposition, that is seemly. It is also seemly not to enter on unnecessary undertakings, nor to omit those that are needed.
111. But it befits the priest especially to adorn the temple of God with fitting splendour, so that the court of the Lord may be made glorious by his endeavours. He ought always to spend money as mercy demands. It behooves him to give to strangers what is right. This must not be too much, but enough; not more than, but as much as, kindly feeling demands, so that he may never seek another's favour at the expense of the poor, nor show himself as either too stingy or too free to the clergy. The one act is unkind, the other wasteful. It is unkind if money should be wanting for the necessities of those whom one ought to win back from their wretched employments. It is wasteful if there should be too much over for pleasure.
Source: On the Duties of the Clergy (New Advent)