Matthew 5:17-20 The Law And The Prophets Fulfilled.
Jesus made crystal clear that he did not come to destroy or abolish the law and the prophets but to fulfill them (v. 17). Much discussion has gone into determining what ‘pleiposai’ or ‘fulfill’ means, but the most determinative point to keep in mind is the context, and whatever ‘fulfill’ means it is certain that it does not mean to destroy, abolish, or terminate. To this Jesus added an ‘Amen’ or ‘assuredly’ to say that nothing could be more sure. He then used the metaphor of the most solid things that we space-time creatures could imagine from the created order in which we live, and that is heaven and earth itself. In effect, these are witnesses to the ‘Amen’ here. The “jot or tittle” are the smallest elements in of both the Hebrew and Greek languages – the jot being the yodh or iota, and the tittle being the least stroke of a pen (v. 18).
From verse 19 we learn what it is that is being fulfilled – namely “the kingdom of heaven.” The reign of God is in fact accomplished through the law and the prophets, and why those who advocate their death will reveal themselves to be the least in the kingdom, but those who teach them will be numbered among the great in the kingdom. We also learn from the context that the righteousness that this entails is something that does not necessarily displace that of the scribes and the Pharisees, in so far as they affirm the validity of the Scriptures and not their man-made traditions, but instead Jesus advocates they did not go far enough (v. 20). Then if we take the larger contexts of Matthew’s account and indeed the whole of the NT, we see that this means that there must be an inward living according to this same standard.