2. The Witness of the Law and the Gospel
Search the scriptures; for in them ye think ye have eternal life: and they are they which testify of me.
John 5:39
Jesus refers to the Scriptures (Old Testament at the time) as a witness to Him.
The Old Testament prophesies the coming of Christ, and the New Testament confirms this fulfillment.
And this gospel of the kingdom shall be preached in all the world for a witness unto all nations; and then shall the end come.
Matthew 24:14
The New Testament is the witness of Jesus and the Gospel message. Jesus said:
All things must be fulfilled which were written in the Law of Moses, and in the Prophets, and in the Psalms, concerning me.
Luke 24:44
This shows that the Old Testament testifies about Christ, just as the New Testament does.