The concept of a day of rest was initiated in the story of Creation. The Genesis account closes with God resting (Hebrew; shabath, [verb] to cease or rest) from all His work, and blessing and sanctifying the seventh day:

"And on the seventh day God ended his work which he had made; and he rested on the seventh day from all his work which he had made. 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." (Genesis 2:2-3).

The themes here are rest and sanctification, and these themes remain the key to an understanding of the whole plan of the Sabbath.

There is no mention of Sabbath as such in the book of Genesis. A seven-day period occurs in connection with the flood (Genesis 7:4‑10; 8:10‑12) and Jacob’s time at Haran (Genesis 29:27,28) but no allusion to a sabbath is intended on these occasions.

Did Adam and Eve observe a sabbath? They had to dress and keep the garden of Eden, but their duties were minimal, and their life appears to have been a continual rest until they were put out of Eden for disobedience. 

Adam then had to work ‘in the sweat of his face’ to overcome the curse, but there is no mention of a special seventh-day rest.

Did Abraham observe a sabbath? Scripture does not indicate whether he did or not. Scripture does indicate that he observed tithing (Genesis 14:20), circumcision (Genesis 17:10), sacrifice (Genesis 22:13), but Abraham’s justification before God came through his faithful believing and not by his keeping of any law (Romans 4:3‑13).