In verse 8, God says "Remember the Sabbath day." Then He tells us that we are to work six days, and the seventh day we are not to work. Verse 11 gives the reason why.

For in six days the LORD made the heavens and the earth, the sea, and all that is in them, and rested the seventh day [not a seventh day.] Therefore the LORD blessed the Sabbath day and hallowed it.

This verse firmly establishes the Sabbath as law, a command to be kept. Yet, it is very clear that this law has its roots in Genesis 2:1-3, for there, God set the example in what He did. He rested, and He blessed the seventh day.

God could have rested at any time. Or, we might say, He needed no rest at all. But He rested. God does not grow weary or become tired. He could have ended the creative cycle at the end of the sixth day, but He did not. Creation did not cease at the end of the sixth day. This is a very important concept. The seventh day is also a creation of God. He kept right on creating, only this time He created by not working, by ceasing.

What did He do? He created a period of rest and of holy time. He created a specific period of time: the seventh day. What He created was just as real as the things created on the other six days. Thus, on the Sabbath, creating continued, but it took on a different form in that it was not outwardly visible. The Sabbath symbolizes to man that God is still creating.