From the Daily Gospel, I found this gem from St. Cyprian concerning "love into action", as a good commentary of today's Gospel reading from Matthew 5:17-19.
Saint Cyprian (about 200-258), bishop of Carthage and martyr
Treatise on jealousy and envy, 12-13
The fulfilment of the Law: love into action
To put on the name of Christ, and not to go in the way of Christ, what else is it but a mockery of the divine name, but a desertion of the way of salvation; since He Himself teaches and says that he shall come unto life who keeps His commandments (Mt 19,17), and that he is wise who hears and does His words (Mt 7,24); that he, moreover, is called the greatest doctor in the kingdom of heaven who thus does and teaches; that, then, will be of advantage to the preacher what has been well and usefully preached, if what is uttered by his mouth is fulfilled by deeds following?
But what did the Lord more frequently instil into His disciples, what did He more charge to be guarded and observed among His saving counsels and heavenly precepts, than that with the same love wherewith He Himself loved the disciples, we also should love one another? And in what manner does he keep either the peace or the love of the Lord, who, when jealousy intrudes, can neither be peaceable nor loving? Thus also the Apostle Paul, when he was urging the merits of peace and charity, and when he was strongly asserting and teaching that neither faith nor alms, nor even the passion itself of the confessor and the martyr, would avail him, unless he kept the requirements of charity entire and inviolate (1Cor 13,1-3).
It would be easy to think that the Lord speaks to a separate group of people, i.e., unbelievers, when he warns of wrongdoing, e.g., "whoever breaks one of the least of these commandments and teaches others to do so will be called least in the kingdom of heaven." It is easy for us to think that our baptism makes us privileged members who can do no wrong. Not so. Being privileged members, much more is required of us. Our baptism gives us the means of sanctifying the world through our witness in deeds and words. In this generation, as much as it had ever been, the world needs a pure witness of charity/love, so that the world might believe that God the Father sent the Son who brings the gift of our salvation. Being recipients of this gift ourselves, we must share this gift with the whole world. To do otherwise would be to turn our backs on those who desperately seek satisfaction in the wrong places, whereas their hearts will only find joy when they rest in the Lord.