Charles Spurgeon Commentary Romans 4:14-15

"For if they that are of the law are heirs, faith is made void, and the promise is made of none effect: for the law worketh wrath; but where there is no law, neither is there transgression." — Romans 4:14-15 (ASV)

For if they who are of the law are heirs, faith is made void, and the promise made of no effect: because the law works wrath: for where no law is, there is no transgression.

So the law is not for justification, but for condemnation. It is the law that reveals sin and that shows sin to be sin; so people can never become right with God by the law.