Amen,
I have always believed that Abraham also had the "Law of Liberty" as a mirror, or guide if you will.
Gen. 26:
4 And I will make thy seed to multiply as the stars of heaven, and will give unto thy seed all these countries; and in thy seed shall all the nations of the earth be blessed;
5 Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws.
I believe this "Law of Liberty" was kept by Abraham and Noah. It was this law that was being "Transgressed" in Gal. 3:19.
"Wherefore then
serveth the law?(Levitical Priesthood)
It was added because of transgressions,
till the seed should come to whom the promise was made;
and it was ordained by angels in the hand of a mediator.
God has His Law of Liberty from creation. Cain was cursed for transgressing it. Sodom was destroyed for transgressing it. Noah and Abraham were blessed for obeying it.
And God "ADDED" the Levitical Priesthood ceremonial, sacrificial "Works of the Law" for remission of sins 430 years after Abraham.
What do you think?