Galatians 3:6. “Even as Abraham believed God, and it was accounted to him for righteousness.”
Four hundred and thirty years before God gave the Law to the Israelites from Sinai, through Moses, Abraham believed God. It was his faith that made him a “friend of God,” and it was his faith that was counted unto him as righteousness.
Did he know all that we know, through the completed Word of God? No. And that makes his faith even more impressive.
You can find further comments on Abraham’s faith–not his works– in Romand 4:1-25; Galatians 3:15-18; and Genesis 12.
Faith. Not works. Not the Law.