Mt 5:17-19
[Jesus said to his disciples,] 17“Do not think that I have come to abolish the law or the prophets. I have come not to abolish but to fulfill. 18Amen, I say to you, until heaven and earth pass away, not the smallest letter or the smallest part of a letter will pass from the law, until all things have taken place. 19Therefore, whoever breaks one of the least of these commandments and teaches others to do so will be called least in the kingdom of heaven. But whoever obeys and teaches these commandments will be called greatest in the kingdom of heaven.”
THE LAW OR THE PROPHETS: The Jews refer to their Scriptures, what we call the Old Testament, as TaNaK, short for Torah (Law), Nebiim (Prophets), and Kethubim (Writings). Often, however, the expression “the law or (and) the prophets” refers to the whole of Scriptures. This is how Jesus and the New Testament writers use it. At times, the aspect of the ethical norm is being emphasized, as when Jesus proclaims the Golden Rule: “Do to others whatever you would have them do to you. This is the law and the prophets” (Mt 7:12). At other times, their prophetic witness to Jesus’ coming is the one being underlined, as when Jesus says that “all the prophets and law prophesied up to John” (Mt 11:13). Luke tells us that the risen Jesus interprets to the two disciples he met on the road to Emmaus what referred to him in all the scriptures, beginning with Moses (the lawgiver) and all the prophets (Lk 24:27).
Very early in the Christian era, there was a debate, at times bitter, over the relationship of Jesus with the Law. To emphasize the absolute preeminence of Christ and his cross and the completeness of his saving death for attaining salvation, Paul proclaims the freedom of the Gospel from the Mosaic Law. Faith in Christ, and not observance of the Law, justifies people before God. The Gentiles who were the majority of Paul’s converts were not to be subjected to the prescriptions of the Law like circumcision, avoiding non-kosher food, or observance of the Sabbath.
Matthew, who writes for Christians mainly of Jewish background, sees the function of Jesus in another perspective. Jesus does not abolish the Law but fulfills it. Fulfilling, however, is not to be equated with the Pharisees’ observance of the commandments in their minute details. Jesus has come to reveal the true meaning of the Law and to emphasize its spirit. The new is not totally different; rather, it is the completion of the old. The “law and the prophets” reveal God, but they are not his definitive revelation; it is Jesus (Heb 1:1-2).