Genesis 2: 1-2
1.Thus the heavens and the earth were finished, and all the host of them.
2.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.
This has got to be one of the craziest text in all of scriptures! We are told all throughout the bible how God is omnipotent, everlasting, etc. How he created the heavens and the Earth ex nihilo (out of nothing) simply with his spoken word in literally six days and that on the seventh day he rested. What does the sabbath actually commemorate according to the scriptures? Genesis 2:3 states that the sabbath is to commemorate the seventh day that followed the six days of creation because on the seventh day God rested and so he sanctified it as a holy day (holiday). Exodus 31:17 reinforces this initial reason why the Hebrews were obligated to keep the sabbath.
It's also funny how some modern apologists try to state that the days of creation were not literally six days, but rather an undetermined amount of time. This was done to try and bring the bible in line with those later discoveries regarding evolution and the age of the Earth. Christians tend to change the meaning of their interpretations of scripture whenever science makes their bible look like what it is; a book of myths. What they once considered literal becomes allegorical or metaphorical, they always find ways to twist it so that it stays in tune with modern day discoveries.
Exodus 31:17 states that after having created the heavens and the Earth in six days the Lord rested on the seventh and was "refreshed". Did he get tired of talking? The bible states in Genesis 1 that he spoke everything into existence, it wasn't like he was down here on his hands and knees planting the garden of Eden. He did a little labor when he made a mud pie out of Adam and later took a rib and made Eve but for the most part it was all done with the spoken word.
Considering that God is omnipotent; to state that he rested makes no sense whatsoever. He supposedly never sleeps nor eats since he is not human and does not possess a physical body, but for some reason he must of broke quite a sweat creating the universe and everything in it. This is just one of the many retarded contradictions of the bible. Here is my theory on this matter, since the bibles myths were created to explain things that were once unknown or in this case a tradition I think that the Hebrews worked six day weeks and took the seventh day off.
This biblical story helps to explain the how this tradition came about no matter how silly it sounds to the rational mindset. By attributing it to God and making it a commandment everyone was obligated to follow it or face the penalty of death. At the same time this story explains the origins of the six day work week. There you have it; a mythological tale to explain one of a societies traditions.