Where, may I ask, did you get this quote?
And even if he said it, he has a point. It may not be a point you may believe but a point nonetheless.
I believe since the Jews have no New Testament (They only have the Old Testament, or the Hebrew Bible as they call it,) they have no Salvation through Christ. They use the Decalogue (or The Ten Commandments) as their way of Morality. No one, not even the most “perfect” human can follow the Ten Commandments. We all fall short in the Glory of God if we use the Decalogue only. Point being, Christians (in my case being a Lutheran,) believe that these Commandments are known as an S.O.S, a fun acronym meaning, in this case, Shows Our Sin. The New Testament, where the works and grace of our Lord Jesus Christ are abundant, is another S.O.S. This time it means Shows Our Salvation.
What Dr. Luther is trying to say is that we shouldn’t make our focus on only God’s Commandments because no matter how hard we try, we will always fail. Instead, Grace and our Faith in Christ save us from Damnation.