Matthew 5:17-18
17 Do not think that I came to destroy the Law or the Prophets; I did not come to destroy but to fulfill; 18 For assuredly, I say to you, till heaven and earth pass away, one jot or one tittle will by no means pass from the law till all is fulfilled.

In these two verses, Jesus reminds his disciples and the crowds gathered around that He is not preaching against the Old Testament (the first five books–“The Law”–and all the prophets’ books). Rather, He is showing them what the Old Testament foretold, and illustrating exactly how to live it. He is the fulfillment of the prophecies about the Messiah, and He is also a great teacher and leader; He is helping His disciples and listeners to better apply the Law to their lives rather than just mouth the words and keep breaking the Commandments.

Verse 18 assures us that until the end of times, nothing in the Law will be changed; God’s Law is what it has been and will be what it is. We need not even embellish the Law with a “jot” or a “tittle,” because God has it all covered. If we try to twist God’s words with some clever interpretations, we will only deceive ourselves. Jesus does not represent a shift away from the Law, but the final installment. He shows us that we cannot save ourselves with righteousness gained from the Law, but the Law is still God’s guideline for living a holy life.

(A side note: Much of Matthew 5 concerns the Pharisees and their rigid adherence to the Law, which actually didn’t respect the spirit in which the Law was written. Jesus takes issue with that. In the selected verses, He emphasizes that He isn’t trying to change the Law, but to uphold its spirit–which showed God’s caring for His people’s safety.)