God did sanctify the day he rested in Genesis 2:3 where it says
And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made. and the commandment in Exodus 20:11 also says
And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made. But there is no commandment to keep the 7th day until Moses and Israel were at the foot of Mt. Sinai. And the commandments themselves explain that the law is given to Israel in Exodus 20:2 saying
I am the LORD thy God, which have brought thee out of the land of Egypt, out of the house of bondage. Thus the commandments and the law are given to Israel.
Romans 5:12-17 explains that there was no law before Moses and I think that is a very clear indication that 7th day keeping was not a law that anybody was commanded to observe before Moses. The passage says:
Wherefore, as by one man sin entered into the world, and death by sin; and so death passed upon all men, for that all have sinned: (For until the law sin was in the world: but sin is not imputed when there is no law. Nevertheless death reigned from Adam to Moses, even over them that had not sinned after the similitude of Adam's transgression, who is the figure of him that was to come. But not as the offence, so also is the free gift. For if through the offence of one many be dead, much more the grace of God, and the gift by grace, which is by one man, Jesus Christ, hath abounded unto many. And not as it was by one that sinned, so is the gift: for the judgment was by one to condemnation, but the free gift is of many offences unto justification. For if by one man's offence death reigned by one; much more they which receive abundance of grace and of the gift of righteousness shall reign in life by one, Jesus Christ.) (Romans 5:12-17)
What more need be said. Paul did not think that Cain or Able or Noah or any of the patriarchs kept the 7th day otherwise he would not have said that there was no law until Moses.
God keep you as free from pain as possible, mmksparbud, God bless and grant you peaceful sleep.