10 I see that you are surprised as I am. And indeed it is a marvellous thing. But I gather as best I can the reason of this thing so strange, and I will not conceal it from you. It is written, “As water quenches fire, so alms quenches sin.” Again it is written, “Shut up alms in the heart of a poor man, and it shall make supplication for you before the Lord.” Again it is written, “Hear, O king, my counsel, and redeem your sins by alms.” And many other testimonies of the Divine oracles are there, whereby it is shown that alms avail much to the quenching and effacing of sins.
Wherefore to those whom He is about to condemn, yea, rather to those whom He is about to crown, He will impute alms only, as though He would say, It were a hard matter for me not to find occasion to condemn you, were I to examine and weigh you accurately and with much exactness to scrutinize your deeds; but, “Go into the kingdom, for I was hungry, and you gave Me meat.” You shall therefore go into the kingdom, not because you have not sinned, but because you have redeemed your sins by alms.
And again to the others, “Go ye into everlasting fire, prepared for the devil and his angels.” They too, guilty as they are, old in their sins, late in their fear for them, in what respect, when they turn their sins over in their mind, could they dare to say that they are undeservedly condemned, that this sentence is pronounced against them undeservedly by so righteous a Judge? In considering their consciences, and all the wounds of their souls, in what respect could they dare to say, We are unjustly condemned.
Of whom it was said before in Wisdom, “Their own iniquities shall convince them to their face.” Without doubt they will see that they are justly condemned for their sins and wickednesses; yet it will be as though He said to them, “It is not in consequence of this that you think, but 'because I was hungry, and you gave Me no meat.'” For if turning away from all these your deeds, and turning to Me, you had redeemed all those crimes and sins by alms, those alms would now deliver you, and absolve you from the guilt of so great offenses; for, “Blessed are the merciful, for to them shall be shown mercy.” But now go away into everlasting fire. “He shall have judgment without mercy, who has showed no mercy.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)