No one said that Abraham followed laws identical to the laws given to Israel as a nation so do not pretend that they have.
Glad to hear that we are agreeing.
How can Abraham bring a sin offering to a Levitical Priest in an earthly Temple and keep annual Feast days when there was not Priest and Temple?
He obviously couldn't, since there were no Levitical priests or temple.
That does not mean that Abraham did not know Gods laws or right and wrong and what sin is when broken and did not know Gods laws of animal sacrifices and sin offerings. Both can be shown and demonstrated in the scriptures.
This originally began as a discussion about the Sabbath. When I stated that there was no prohibition for working on the Sabbath until the manna incident, the response was "Abraham kept the laws." Now, if you want to support me on that, that's fantastic. If you want to claim that Abraham kept the sabbath, then we are going to continue disagreeing, because you cannot point to anywhere in Genesis where anyone is instructed not to work on the seventh day.
Moral law falls under the description of "Love your neighbor as yourself." It is designed to prevent harm to our fellow human beings. Keeping the Sabbath is NOT moral law. Keeping the sabbath is an expression of love for God, and there are many ways to show love of God -- it is not one comprehensive list. One person may come from a culture where loving God means singing in a state of ecstacy with their palms raised high. Another person may show their love for God by spending hours studying sacred texts. For Jews, one of the ways we show our love of God is by keeping the Sabbath. But it is not a universal law.
If you want to keep the Sabbath, if it brings you closer to God, I say go for it. But it is not a requirement, not for you, and not for any of the nations of the world. It is NOT the same thing as refraining from theft, murder and adultery. It is NOT a universal law.