Shalom and thank you for your question! The first reference in the Torah to Sabbath observance is the account of Creation in Genesis 2:1-3. “And on the seventh day the L-rd completed all that He had made. And He rested on the seventh day from all his labours that He had done. And the L-rd blessed the seventh day and sanctified it, for then He desisted from all His labours that He created to do.”
These sentences became part of the Kiddush, the prayer recited over a goblet of wine at the Sabbath meals.
Observing the Sabbath is also one of the Ten commandments given on Mount Sinai. It is the fourth one, “Remember the Sabbath day and keep it holy,” which was bequeathed to the Jewish people by G-d at that time.
The classic Torah commentator Rabbi Shlomo Yitzchaki, (known by the acronym ‘Rashi’, ) explains that the commandment was given over at Marah, in the Sinai desert, and there are commentators who maintain that since Abrahamic times there was a general concept of Sabbath among the Jewish people, but the details of it’s observance were indeed given at Marah.
We need to understand that the evolution of the Jewish nation into one with specific laws and practices was a process in stages.
Abraham was called the ‘Hebrew ‘ because in Hebrew the word means ‘to one side.’
Abraham was monotheistic in a generation of idol worshippers.(Till today idols are still worshipped in some parts of the world. )
So he taught his family and the people around him to believe in a G-d that cannot be seen or truly apprehended. He discovered G-d at a tender age because he searched for Him.(Midrash.) Thus, he had an open line of communication with G-d, and Kabbalistic teachings explain that he and the rest of the forefathers of the Jewish nation kept all the commandments of the Torah on a spiritual level. 70 Jewish souls came down to Egypt and multiplied greatly, while the descendants of Levi lived in Goshen and were not enslaved, they instead were occupied with studying the spiritual wisdom passed down by the forefathers. The whole Jewish nation maintained their Hebrew names and distinct garb even while evslaved physically and influenced in other ways by the Egyptian culture!
The nation as a whole however, received the Ten commandments at Sinai and were subsequently taught all the details of Torah observance by Moses.
The body of Torah knowledge has developed since then continuously. The Torah gives principles of how to keep the Sabbath, but each generation has different circumstances for which scholars need to use the principles given in the Torah to decide current practice.
One example…the refrigerator, or other electrical appliances. At the giving of the Torah these did not exist, but the principles of Sabbath observance did. Torah scholars ascertained the manner in which technology may be used on the Sabbath and the manner it may not. Use of technology on the Sabbath and festivals is different again in the context of illness and hospitals. Thus the body of Torah knowledge increases through the generations. New advances in technology mandate additional application of Torah law.
