Christ referred to the law and the prophets concerning their witness to his death to the two disciples on the road to Emmaus: “And he said to them, O foolish ones, and slow of heart to believe all that the prophets have spoken! Was it not necessary that the Christ should suffer these things and enter into his glory? And beginning with Moses and all the Prophets, he interpreted to them in all the Scriptures the things concerning himself” (Luke 24:25-27). What did Jesus mean in Luke 24:27 that he expounded all the Scriptures concerning himself “beginning with Moses and all the Prophets”? In the follow-up statement in 24:44 Jesus explained that what he previously spoke from the Old Testament “the Law of Moses, the Prophets, and the Psalms” was only what was “written about me.” Jesus probably preached the prophecies and the types from the Old Testament including Genesis 3:15, Psalm 22, and Isaiah 53 as well as the Passover Lamb in Exodus 12:5, the Rock that Moses struck in Exodus 17:6, and the Brazen serpent in Numbers 21:9. These anti-types are referred to in the New Testament in John 3:14-15, 1 Corinthians 5:7, and 1 Peter 1:19. Paul next in Romans three elaborated on the witness of the law and prophets to Christ’s death in Romans 3:21.
The reference to the Old Testament as “the law and the prophets” (Romans 3:21) is a reference to the two major sections of the Hebrew Bible, which prepares the way for Romans four. In Romans four, Paul discussed Abraham and David, two representatives of these two sections of Scripture. The law in Romans 3:21 refers to the first five books, where Abraham was justified by faith in Romans 4:3. The prophets in Romans 3:21 refers to all the rest of the Old Testament where David was justified by faith in Romans 4:8. Both the law and the prophets “witnessed” to this one way of being declared righteous before God which now in progressive revelation is publicly revealed through the death, burial, and resurrection of Christ.
Leon Morris brought out the significance of Paul’s reference to “the prophets.” Morris wrote: Paul is making the point that the gospel is no afterthought. God had always planned to save people by the way of grace. It is the making of this known that is recent. That it was always God’s way is clear from the fact that testimony is borne to it by the Law and the Prophets, an expression that means the whole Old Testament (cf. Matt. 5:17; 22:40; Luke 24:27). The law was the heart of the Jewish religious system and the prophets were its outstanding religious teachers. And both, says Paul, point to the truth that right standing comes from God. Notice the perfect tense πεφανέρωται [“has been manifested”]; the manifestation is of continuing force. Some see a reference to the incarnation (e.g., Lagrange), but it is rather to be understood as the atonement.[1]
[1] Leon L. Morris, The Epistle to the Romans (Grand Rapids: W.B. Eerdmans; Inter-Varsity Press, 1988), 174.