Moses says that he whose actions conform to the righteousness required by the Law shall live by that righteousness.
and, as it turned out, the very Commandment which was to bring me life, brought me death.
and the Law has nothing to do with faith. It teaches that »he who does these things shall live by doing them.«
not having a righteousness of my own, derived from the Law, but that which arises from faith in Christ–the righteousness which comes from God through faith.