To "Rest" is to be balanced in law, and it's a parallel to the Yoke of Christ. The Sabbath is a day of observation, as it is described to precede the first day of the week, in spite of what many people do to oppose it, and say that Sunday is the Sabbath day. They argue between what is the Lord's day and the Sabbath day, and only to separate the two as if they are different.
Matthew 28:1
King James Version (KJV)
28
In the end of the sabbath, as it began to dawn toward the first day of the week, came Mary Magdalene and the other Mary to see the sepulchre.
The Sabbath is recognition of the Covenant made in the Beginning, which was of God and for all generations to follow. His Seed originated in the Beginning, not afterwards. The Sabbath was established as a day of recognition, albeit it is a perpetual ongoing Covenant that never seizes with God if man remains obedient. It's only man that breaks the covenant.
Today's, Sabbath worship is merely a weekly occasion when it should be a continual Resting in Christ's Covenant. We are not to break it off when we leave Church and then re-establish it on Saturday when we go to Church.
The number 7 is as a Covenant of two others made in it. There are many parallel's to a Sabbath, and the Rest in it. Land is to be given a rest every seven years but man has made ways around this with share cropping, or alternate crops between different plants.
This is a form of cheating God and working without His given Sabbath rest's. We humans will experience a Sabbath rest during the Millennium because we will be resting in Him and without man's inventions when He takes it away from us, as it all belongs to Him. The earth will rest for the seventh-thousand year period as a Sabbath Rest. This coincides with the fact that the Creation on Earth is only 6000 yrs thus, plus or minus a few years to date.
The earth itself may be much older but the human population is dated as man lives in "time" and apart from Eternity. When "time" is seized by God, we will then see the beginning of the Eighth day, or better said, Eternity, and without time as man has created.
The Sabbath will someday be kept as it should, and with full understanding of it.
Thanks