Rom 1:2, Gal 3:16, Mt 13:16-17, Lk 24:27, 32, 44-45, Jn 5:39, Jn 20:31, Rom 10:4

God's promises delivered through the prophets were all yes in Christ. That is, it was fulfilled in Christ. (2 Cor 1:20, Rom 1:2, Gal 3:16)

2 Cor 1:20 For all the promises of God in him are yea, and in him Amen, unto the glory of God by us.

Rom 1:2 (Which he had promised afore by his prophets in the holy scriptures,)

Gal 3:16 Now to Abraham and his seed were the promises made. He saith not, And to seeds, as of many; but as of one, And to thy seed, which is Christ.

Jesus Himself also made known that the prophecies of the prophets about the Christ had been fulfilled in Himself. (Mt 13:16-17, Lk 24:27,32,44-45)

Mt 13:16 But blessed are your eyes, for they see: and your ears, for they hear. 17 For verily I say unto you, That many prophets and righteous men have desired to see those things which ye see, and have not seen them; and to hear those things which ye hear, and have not heard them.

Lk 24:27 And beginning at Moses and all the prophets, he expounded unto them in all the scriptures the things concerning himself. 32 And they said one to another, Did not our heart burn within us, while he talked with us by the way, and while he opened to us the scriptures? 44 And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me. 45 Then opened he their understanding, that they might understand the scriptures,

Jesus made it clear that the Old Testament was the testimony of Himself. (Jn 5:39)

Jn 5:39 Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.

After all, the entire Bible tells us that Jesus is the Christ and that we are saved by believing in that fact. (Jn 20:31)

Jn 20:31 But these are written, that ye might believe that Jesus is the Christ, the Son of God; and that believing ye might have life through his name.

Also, Christ is the end of all Old Testament laws. (Rom 10:4)

Rom 10:4 For Christ is the end of the law for righteousness to every one that believeth.