Why seven? The number is obviously important, or else God would not have employed it so often. Seven churches in Revelation; seven pairs of clean animals into the ark; seven days of Passover. Seven years for love. Seven lamps of light. Seven days for cleansing. Seven years in Hebron. Seven seals of the end time.
The Creation week, too, follows the rule of seven. Notice the following verses:
And God saw every thing that he had made, and, behold, it was very good. And the evening and the morning were the sixth day. Thus the heavens and the earth were finished, and all the host of them. 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. And God blessed the seventh day, and sanctified it: because that in it he had rested from all his work which God created and made.(Genesis 1:31-2:3 KJV)
For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.(Exodus 20:11 KJV)
Of that seven-day week, God chose the seventh day as the day of rest - His Sabbath day.
The word "sabbath", as a common noun, really means "rest". The "sabbaths" as outlined in Leviticus -- those for agriculture, those for feasting, and those for solemnity -- were all days when the children of Israel did no work. These were later done away with at the cross (Colossians 2:14-17) because had fulfilled the shadow.
The Passover was followed by the seven days’ feast of unleavened bread. On the second day of the feast, the first fruits of the year’s harvest, a sheaf of barley, was presented before the Lord. All the ceremonies of the feast were types of the work of Christ. The deliverance of Israel from Egypt was an object lesson of redemption, which the Passover was intended to keep in memory. The slain lamb, the unleavened bread, the sheaf of first fruits, represented the Saviour.
(Desire of Ages, p. 77)
But the Sabbath -- the proper noun -- is everlasting. "And it shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the LORD (Isaiah 66:23 KJV)." The Sabbath is the day when we specifically put aside earthly things, and really commune with God. We rest from earthly cares, and focus on God.
Remember the sabbath day, to keep it holy. Six days shalt thou labour, and do all thy work: But the seventh day is the sabbath of the LORD thy God: in it thou shalt not do any work, thou, nor thy son, nor thy daughter, thy manservant, nor thy maidservant, nor thy cattle, nor thy stranger that is within thy gates: For in six days the LORD made heaven and earth, the sea, and all that in them is, and rested the seventh day: wherefore the LORD blessed the sabbath day, and hallowed it.(Exodus 20:8-11 KJV)
God wants us to be perfect. "Be ye therefore perfect, even as your Father which is in heaven is perfect (Matthew 5:48 KJV)." Thus He made the Sabbath: a day where we may spend time with Him, and learn and know His will for our lives and for the world.
Pre-sin, the communion of Sabbath was a time for Adam and Eve to come to a fuller knowledge of their Lord -- to spend time with Him, and learn and know His will for their lives and for the world. "And he said unto them, The sabbath was made for man, and not man for the sabbath:" (Mark 2:27 KJV).
The idea was perfection. Learning more of God and His will by focusing fully on Him was why the Lord rested. He was giving us an example of attitude and behavior.
Would you like to acknowledge God's day of perfection and rest as the seventh day, and follow His example by keeping it holy? God wants to spend time with YOU.