It's because there is no end to the 7th day. GOD finished his work and is now at rest. We who believe enter into that rest with GOD and abide there every day instead of pretending it's only one day of the week.
A blessed sabbath rest to everyone who believes.
Actually, you are half-right. God is still resting from His Creative works. The first chapter was about God. He, Him, His...Even to Genesis ch. 2 verse 3... It's not everyday that we enter into the Sabbath rest.. For the Sabbath is the 7th day. That is when God rested,, we see that He worked every other day. So it is with mankind and the 4th Commandment... six days you shalt labor and do all thy work, but the seventh is the sabbath, in it you shall do no work.
God blessed the Sabbath after it had ended. The Bible says God rested,,,,then,,, He blessed the seventh day.
The Sabbath is the 7th day,,, no where in scripture does it say the Sabbath is every day. It's not. Just because God rested from His work does not mean we rest everyday. We don't,, we are to do all our work during the first 6 days of the week,, the last day, 7th, is the sabbath,, that won't ever change.
God will make a new heaven and a new earth ( He will be working soon) and then He will rest again,, only this time forever. And we will be keeping Sabbath in the new earth, because of Gods new Creative works!
Good job,, have a nice sabbath!