5 Must they then lose all they have? He said, “Let them communicate,” not “Let them give the whole.” Let them keep for themselves as much as is sufficient for them, let them keep more than is sufficient. Let us give a certain portion of it. What portion? A tenth? The Scribes and Pharisees gave tithes for whom Christ had not yet shed His Blood. The Scribes and Pharisees gave tithes; lest haply you should think you are doing any great thing in breaking your bread to the poor; and this is scarcely a thousandth part of your means.
And yet I am not finding fault with this; do even this. So hungry and thirsty am I, that I am glad even of these crumbs. But yet I cannot keep back what He who died for us said while He was alive. “Unless your righteousness exceeds the righteousness of the Scribes and Pharisees, you shall in no case enter into the kingdom of heaven.” He does not deal softly with us; for He is a physician, He cuts to the quick. “Unless your righteousness exceeds the righteousness of the Scribes and Pharisees, you shall in no case enter into the kingdom of heaven.”
The Scribes and Pharisees gave the tenth. How is it with you? Ask yourselves. Consider what you do, and with what means you do it; how much you give, how much you leave for yourselves; what you spend on mercy, what you reserve for luxury. So then, “Let them distribute easily, let them communicate, let them lay up in store for themselves a good foundation against the time to come, that they may hold on eternal life.”
Source: Sermons on Selected Lessons of the New Testament (New Advent)