He obeyed BECAUSE he had faith in God.
Again--I don't find anyone taking issue with that claim.
I agree--Abraham obeyed because he believed God.
I'm not sure how that somehow discounts the testimony of the Lord--who testified the promises were due to the obedience of Abraham:
Genesis 26:4-5---King James Version
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.
That's God's grace because of Abraham's obedience. That's a faith with works, or--a living faith.
We receive His grace the same way--through a living faith, obedience to Jesus Christ.
Hebrews 5:9---King James Version
9 And being made perfect, he became the author of
eternal salvation unto all them that obey him;
Which he did of his own free will. Did God command him to tithe?
Yes--and that can be shown--which you have not addressed:
Malachi 3:7-12---King James Version
7 Even from the
days of your fathers ye are gone away from
mine ordinances, and have not kept them. Return unto me, and I will return unto you, saith the Lord of hosts. But ye said, Wherein shall we return?
8 Will a man rob God? Yet ye have robbed me. But ye say, Wherein have we robbed thee?
In tithes and offerings.
9 Ye are cursed with a curse: for ye have robbed me, even this whole nation.
10 Bring ye all the tithes into the storehouse, that there may be meat in mine house, and prove me now herewith, saith the Lord of hosts, if I will not open you the windows of heaven, and pour you out a blessing, that there shall not be room enough to receive it.
11 And I will rebuke the devourer for your sakes, and he shall not destroy the fruits of your ground; neither shall your vine cast her fruit before the time in the field, saith the Lord of hosts.
12 And all nations shall call you blessed: for ye shall be a delightsome land, saith the Lord of hosts."
This was a one time tithe from Abe, as thanks to God for his victory over his enemies in battle.
Then tithing had it's roots in the gospel of Jesus Christ--not the Mosaic Law.
they went away from God's ordinances "SINCE the days of your fathers." That lets out Abe, who obeyed God.
How so? Abraham was one of the fathers. SINCE the days of the fathers--- includes the fathers, and their days.
The Israelites went astray time and time again, since they left Egypt. THESE are the the "fathers" referenced in Malachai. NOT Abe, who obeyed God.
The accusation was not against Abraham, or the fathers--but against those who did not obey God, from the days of the fathers.
Sorry, but Abraham was centuries before the Covenant through the Mosaic Law. Abraham lived under the gospel, not the Mosaic Law. Tithing came through the gospel in Abraham's time.