Did Abraham Tithe under the Law?

Gal 4:4-5 But when the fullness of the time was come, God sent forth his Son, made of a woman, made under the law, to redeem them that were under the law, that we might receive the adoption of sons.

"to redeem them that were under the law" - was this only referring to people starting from Moses, or did Adam need redemption from the law as well? Of course Adam needed redemption from the law just as much as Moses needed redemption from the law, just as much as Abraham needed redemption from the law. Remember the law was not new when God gave it to Israel and Moses - the nation of Israel was the one that was new. God's plan for redemption from the law started in Genesis 3, not with Moses.

Conclusion:
Yes, Tithing was under the law.