“The Old Testament is Law. The New Testament is Gospel.”
That seems to be the most common view of the relationship between the two Testaments.
Paul appears to confirm this in Romans 10 when he quotes Moses to illustrate attempts at salvation via law-keeping. “The man who does those things shall live by them” (Romans 10:5 quoting Leviticus 18:5)
That settles that then, doesn’t it.
Oh, wait, he quotes Moses again in the next verses to explain salvation by faith in Christ (Rom 10:6ff quoting Deuteronomy 30:12ff).
Either Moses and Paul are very confused; or we are.
I think I’ll take the safer option there.
Moses related Law and Gospel in the Old Testament in the same way as Paul did in the New.
Oh, and Jesus too! (Luke 10:28).