אלמלא שמרו ישראל שתי שבתות מיד נגאלים ]שבת קיח:[
If Klall Yisroel would keep two Shabbosos they would be immediately redeemed. [Mesechtoh Shabbos 118:]
Seforim say it must be two Shabbosos since every Shabbos needs a preparation of the previous Shabbos!
The Meor Einayim says that each Shabbos is “Yonek” - nurtures, from the previous Shabbos. If so, where does the first Shabbos, Shabbos Bereishis Yonek from? To this he answers that it is Yonek from Shabbos Eiloeh - the Heavenly Shabbos.
The Chidushei Harim ZY”A says every Shabbos is an “Olam Chodosh”, a new world. We must make sure that the Shabbosos are connected to each other.