Do well to him that is lowly, but give not to the ungodly: hold back your bread, and give it not to him, lest he overmaster you thereby: for else you shall receive twice as much evil for all the good you shall have done to him.
Read Chapter 12
Gregory The Dialogist
The mind should first be predisposed to patience, and then either much or all should be given bountifully, otherwise, when the inroad of want is borne with but little equanimity, then, both the reward of previous bounty could be lost and subsequent murmuring might bring even worse ruin on the soul. Just in case they should give nothing at all to those on whom they ought to bestow something, let them hear what is written: "Give to everyone who asks of you." And, just in case they should give something, however little, to those on whom they ought to bestow nothing at all, let them hear what is also written: "Give to the good person, and do not receive a sinner; do well to the one who is lowly, and do not give to the ungodly." And again, "Set out your bread and wine on the burial of the just, but do not eat and drink with sinners."
For the one who gives his bread and wine to sinners provides assistance to the wicked because they are wicked. This is also why some of the rich of this world nourish players with profuse bounties, while the poor of Christ are tormented with hunger. He, however, who gives his bread to one that is indigent, though he is a sinner, not because he is a sinner but because he is a human being, does not in truth nourish a sinner but a poor righteous person, because what he loves in him is not his sin but his nature. Those who already distribute compassionately what they possess are to be admonished also so that they might learn how to be vigilant, lest, when they redeem by alms the sins they have committed, they commit others that will still require redemption; otherwise they might suppose that the righteousness of God is for sale, thinking that if they take care to give money for their sins, they can sin with impunity. - "Pastoral Rule 3.20"