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.”
I HAVE COME... TO FULFILL: A passage at the end of Jesus’ series of parables is often understood to refer to the evangelist who wrote the Gospel. He is a scribe instructed in the kingdom of heaven who brings from his storeroom both the new and the old (cf Mt 13:52). He represents the Christian community which adheres to the letter of the Torah in opposition to a more liberal interpretation such as those represented by Stephen (Acts 7:48ff) and by Paul (Gal 2:2-6).
However, the fulfillment of the Torah does not refer to the interpretations of the Jewish rabbis; the Law is only fulfilled through Jesus and his community. To the Law, Matthew adds the prophets to show the continuity of the revelation of the will of God running through history up to Jesus.
When Jesus “fulfills” the Law and the prophets, he does not mean the literal following of the minute regulations. In fact, Jesus at times violates the Sabbath rest or gives little importance to ritual cleanliness. Fulfillment means that in Jesus there has come what the Law and the prophets only announced. In him has come the fullness that is intended in them but not attained.