Romans 3:21b

But now a righteousness from God, apart from law, has been made known, to which the Law and the Prophets testify.

(v21, NIV)

How do the law and the prophets testify to this righteousness apart from the law? Well, what does the law talk about? The law is God's standard, which we can never measure up to. From it, we hear and know of God's requirements, from which we could never live up to. We may try and try but we always fail. Fortunately, the prophets tell us about the coming messiah. They tell us about Jesus and we know what Jesus came to do. Jesus came on a mission to save us. Jesus lived a perfect life which none of us could live and then died, bearing all our sins, so that a swap could take place. In this saw, we receive Jesus' righteousness and he pays the penalty for our sins. This is the righteousness from God; the righteousness of Jesus is given to us.