Righteousness from the law: see Leviticus 18:5, You shall keep my statues and my ordinances; by doing so one shall live: I am the Lord.
Righteousness is not something human beings are capable of achieving on their own. God's help is necessary: see Deuteronomy 30:11-14, Surely, this commandment that I am commanding you today is not too hard for you, nor is it too far away. It is not in heaven, that you should say, "Who will go up to heaven for us, and get it for us so that we may hear it and observe it?" Neither is it beyond the sea, that you should say, "Who will cross to the other side of the sea for us, and get it for us so that we may hear it and observe it? No, the word is very near to you; it is in your mouth and in your heart for you to observe.
Faith is in your heart but cannot be confined there. As Boring & Craddock put it in their People's New Testament Commentary: "'Internal' faith without 'external' confession is as defective as external pretense without faith in the heart...."