The first mention of rest on the seventh day is found in Genesis 2:1-3. The actual term “Sabbath” is not used, but the concept is clearly there in the related verb for “rest” on the seventh day (Saturday).
Thus the heavens and the earth were finished, and all the host of them. And on the seventh day God finished His work that He had done, and He rested on the seventh day from all His work that He had done. So God blessed the seventh day and made it holy, because on it God rested from all His work that He had done in creation. (Genesis 2:1-3)
Some have said, “Look! The Sabbath was given to man from the very beginning.” Look more closely. Who rested on the seventh day, God or man? God rested. Human rest was not the subject in the Genesis story. God rested and set aside that day as sacred, but Genesis offers no record of man being commanded to keep the Sabbath. Did Adam or the other great men of Genesis know that God had sanctified the Sabbath? Genesis itself gives no answer. It never again mentions a day of rest and makes no further reference to the seventh day.
Genesis never again mentions a day of rest.
We may well wonder, “Then why did Genesis record the importance of the seventh day?” The answer appears in Exodus. The first time the word “Sabbath” is used in our English Bible is in Exodus 16:23. This was shortly before the giving of the Ten Commandments, of which the Sabbath was the fourth commandment.
Remember the Sabbath day, to keep it holy. Six days you shall labor, and do all your work, but the seventh day is a Sabbath to the LORD your God. On it you shall not do any work, you, or your son, or your daughter, your male servant, or your female servant, or your livestock, or the sojourner who is within your gates. For in six days the LORD made heaven and earth, the sea, and all that is in them, and rested on the seventh day. Therefore the LORD blessed the Sabbath day and made it holy. (Exodus 20:8-11)
In making the seventh day special for Israelites as His chosen nation, God gave this reason: He too rested on the same day (Exodus 20:11). If Moses had not recorded the background information in Genesis, God’s reason in Exodus would have made little sense.