A Perpetual Covenant
Wherefore the children of Israel shall keep the sabbath, to observe the sabbath throughout their generations, for a perpetual covenant. It is a sign between me and the children of Israel for ever: for in six days the Lord made heaven and earth, and on the seventh day he rested, and was refreshed.
- Exodus 31:16-17 (KJV)
Perpetual means "never ending or changing".
There will always be Sabbaths in other words.
Some people think that Sabbaths are "Jewish", and not for us today. But that's not true.
Sabbaths were established well before the Ten Commandments were given on Mount Sinai.
While in the desert the Jews were given twice the amount of bread on Friday, so that they could rest on sabbath day.
See, for that the Lord hath given you the sabbath, therefore he giveth you on the sixth day the bread of two days; abide ye every man in his place, let no man go out of his place on the seventh day.
- Exodus 16:29-30 (KJV)
This sabbath was kept before the Ten Commandments were written in stone (by God's own finger).
Even Ellen White showed that Adam and Eve kept the sabbath also.
Adam kept the Sabbath in his innocence in Eden; he still kept it when, fallen yet repentant, he was driven from the Garden. All the patriarchs from Abel to Noah, to Abraham, to Jacob kept the Sabbath. When the Lord delivered Israel from Egypt, He proclaimed His law to the emerging nation.
- Ellen White, Love under fire, p. 188
The Ten Commandments weren't just "invented" for the Jews. They were merely proclaimed in a very powerful way to establish the Old Covenant.
God doesn't change, and nor will the Ten Commandments (which are a reflection of His Character).
For I am the Lord, I change not; therefore ye sons of Jacob are not consumed.
- Malachi 3:6 (KJV)
No other day was ever given.
For if Jesus had given them rest, then would he not afterward have spoken of another day.
- Hebrews 4:8 (KJV)
God says that His Sabbaths will always be.
For as the new heavens and the new earth, which I will make, shall remain before me, saith the Lord, so shall your seed and your name remain. 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 66:22-23 (KJV)
The Sabbath is therefore a set day for worship and fellowship.
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)
This used to be well established by the early churches, but around 321 A.D. it was changed to Sunday. This change is sometimes also called a mark (of authority).
So now you know. 
Happy Sabbath everyone.