14 See then what this, “Give us oil,” is. They were told “Go ye rather to them that sell.” In that you have been used to live upon the praises of men, you do not carry oil with you; but we can give you none; “lest there be not enough for us and you.” For scarcely do we judge of ourselves, how much less can we judge of you? What is “scarcely do we judge of ourselves”? Because, “When the righteous King sits on the throne, who will glory that his heart is pure?” It may be you do not discover anything in your own conscience; but He who sees better, whose Divine glance penetrates into deeper things, discovers it may be something, He sees it may be something, He discovers something.
How much better may you say to Him, “Enter not into judgment with Your servant”? Yea, how much better, “Forgive us our debts”? Because it shall be also said to you because of those torches, because of those lamps; “I was hungry, and you gave Me meat.” What then? Did not the foolish virgins do so too? Yea, but they did it not before Him. How then did they do it? As the Lord forbids, who said, “Take heed that you do not your righteousness before men to be seen of them, otherwise you have no reward of your Father which is in heaven: and when you pray, be not as the hypocrites, for they love to pray, standing in the streets, that they may be seen of men.
Verily I say unto you, they have received their reward.” They have bought oil, they have given the price; they have bought it, they have not been defrauded of men's praises, they have sought men's praises, and have had them. These praises of men aid them not in the judgment day. But the other virgins, how have they done? “Let your works shine before men, that they may see your good works, and glorify your Father which is in heaven.” He did not say, “may glorify you.” For you have no oil of your own self. Boast yourself and say, I have it; but from Him, “for what have you that you have not received?” So then in this way acted the one, and in that the other.
Source: Sermons on Selected Lessons of the New Testament (New Advent)