Matthew 5:17 (ESV) … “Do not think that I have come to abolish the Law or the Prophets; I have not come to abolish them but to fulfill them.”
As the Lord continued His sermon, He turned His attention to the Mosaic law—the foundation of Jewish national life and the moral, ceremonial, and religious code under which He lived. First He stated His personal appreciation of God’s law. He had not come to destroy the law, but to fulfill it.
The Jews counted 613 separate edicts in the Mosaic law and there never was a single moment when the Lord Jesus did not absolutely fulfill in every detail every commandment. As a baby and as a boy, as a teenager and in the prime of life, at home, at school, at work, at play, as a son and as a brother, as a neighbor and as a friend, as a village carpenter, as an itinerant preacher, in secret and in public, when surrounded by family and friends and when confronted by formidable foes—at all times, in all places, in all ways, He kept the law of God. He kept it in letter and in spirit. He kept the law in its injunctions and in its intentions. He kept it because it was His nature to keep it. He would never dream of not keeping it. It was His Father’s will and Jesus always did those things that please the Father (see John 8:29).
In Old Testament times the most sacred object connected with Israel’s richly symbolic system of worship was the ark of the covenant that stood within the holy of holies, which was behind the veil. Inside that ark was an unbroken copy of the Mosaic law. Upon that ark rested, as upon a throne, the shekinah glory cloud, the visible token of the presence of God. That ark represented Christ; in His heart resided God’s unbroken law; upon Him rested the enthroned Spirit of God, now present on earth in a marvelously new way.
“I saw the Spirit,” said John the Baptist. That statement was unique, for in His essence the Holy Spirit cannot be seen; He is eternal and invisible. But the Baptist said, “I saw the Sprit descending from heaven like a dove, and it abode upon him” (John 1:32). The word translated “abode” is mend, one of the favorite words of the apostle John. He used it forty-one times in his Gospel, where it is rendered “abide” or “abode” twenty-two times, “dwell” five times, “remain” or “remaining” five times, “continue” three times, “endure” once, “abide still” once, “tarry” three times, and “be present” once. In his Epistles he used menō twenty-six times.
It was that visible coming of the Holy Spirit to abide upon the Lord Jesus that identified Him to John the Baptist as the Son of God. The Baptist said, “I knew him not: but he that sent me to baptize with water, the same said unto me, Upon whom thou shalt see the Spirit descending, and remaining [menō] on him, the same is he” (John 1:33). The Holy Spirit could enthrone Himself upon Jesus because of the unbroken law hidden in Jesus’ heart (Psalm 119:11). In the heart of this One, and this One alone, God’s Word could be found intact and unbroken.
God’s law had two parts: the moral law and the ceremonial law. In His amazing life the Lord Jesus fulfilled the demands of the moral law. In His death He fulfilled the details of the ceremonial law, which was chiefly concerned with sacrifices and offerings.
He fulfilled the rich symbolism of the sin offering, the trespass offering, the meal offering, the peace offering, and the burnt offering. Jesus was the goat that was slain on the day of atonement, whose blood was taken into the holy of holies; and He was the scapegoat upon which were laid the sins of the people before it was led away into “a land not inhabited” (Leviticus 16:22). He was the bird that the cleansed leper brought to be slain in his stead; and He was the other bird that the cleansed leper brought to be dipped in the blood of the first bird before being set free to fly heavenward for home. Jesus was the unleavened bread of the Passover, and He was the paschal lamb. His were the ashes of the red heifer, and His was the blood that was shed for sin. The red rivers that poured from ten thousand times ten thousand sacrifices were but a feeble type of His precious blood.
Well could He announce: “Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil” (Matthew 5:17).
Jesus fulfilled the prophets as well as the law. The prophets in glory must have been overjoyed at the life Jesus lived on earth. “I wrote about His suffering,” Isaiah might have cried, reciting Isaiah 53, “and look how He has fulfilled my words to the letter!” David might have added, “Yes, and Psalm 22 as well, and Psalm 69.” And Zechariah: “He has also fulfilled my prophecy.” God would have commented, “This is my beloved Son,” and the angels would have gazed down in wonder, for these are “things the angels desire to look into” (1 Peter 1:12). 
 Phillips, J. (2014). Exploring the Gospel of Matthew: An Expository Commentary (Mt 5:17). Kregel Publications; WORDsearch.