The Sabbath commandment was given by God, along with the other 9
commandments, to the Israelites at Sinai: Ex 20:8-11 "Remember the Sabbath day
by keeping 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,
neither you, nor your son or daughter, nor your manservant or maidservant, nor
your animals, nor the alien within your gates. For in six days the LORD made the
heavens and the earth, the sea, and all that is in them, but he rested on the
seventh day. Therefore the LORD blessed the Sabbath day and made it holy."
The Exodus account of the commandments refers to the creation and the fact that God rested on the seventh day as the reason for the Sabbath day. Interestingly, this was the way the Israelites needed to learn to rest in the Lord. Please note that the commandments forbade the Israelites from doing "any work" on that holy day.
A notion that this was a creation ordinance is quite possible. The text definitely allows for this explanation. It also allows for the idea that since God is the Creator, we are to worship Him as such.
The 10 commandments are again recorded in the book of Deuteronomy. Here Moses is giving his last speech to the Israelites. Again, the Sabbath is mentioned as the 4th commandment. But there is a different reason given for keeping the Sabbath this time. Deut 5:12-15 "Observe the Sabbath day by keeping it holy, as the LORD your God has commanded you. 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, neither you, nor your son or daughter, nor your manservant or maidservant, nor your ox, your donkey or any of your animals, nor the alien within your gates, so that your manservant and maidservant may rest, as you do. Remember that you were slaves in Egypt and that the LORD your God brought you out of there with a mighty hand and an outstretched arm. Therefore the LORD your God has commanded you to observe the Sabbath day." NIV
Interestingly, the reason given in this rendition of the commandments is not creation, but the Israelites' deliverance from Egypt! It is also interesting to note that throughout the books of Exodus, Leviticus, Numbers and Deuteronomy, God is clearly addressing the Israelites when He commands them to observe His Sabbaths. Ex 31:12-32: "Then the LORD said to Moses, "Say to the Israelites, 'You must observe my Sabbaths. This will be a sign between me and you for the generations to come, so you may know that I am the LORD, who makes you holy. "'Observe the Sabbath, because it is holy to you. Anyone who desecrates it must be put to death; whoever does any work on that day must be cut off from his people. For six days, work is to be done, but the seventh day is a Sabbath of rest, holy to the LORD. Whoever does any work on the Sabbath day must be put to death. The Israelites are to observe the Sabbath, celebrating it for the generations to come as a lasting covenant. It will be a sign between me and the Israelites forever, for in six days the LORD made the heavens and the earth, and on the seventh day he abstained from work and rested.'" When the LORD finished speaking to Moses on Mount Sinai, he gave him the two tablets of the Testimony, the tablets of stone inscribed by the finger of God."
Click here to go to: Chapter 5: The Sabbath in the ceremonial law.