Observes Calvin:3 "Should any one expect some secret meaning in the number 'seven' this being in Scripture the number for perfection it may have been selected not without cause to denote perpetuity[!]. In accordance with this, Moses concludes his description of the succession of day and night on the same day on which he relates that the Lord rested from His works." Genesis 2:1-3.
Calvin continues: "Another probable reason for the number [‘seven’] may be that the Lord intended that the Sabbath never should be completed before the arrival of the last[!] day. We here begin our blessed rest in Him, and daily make new progress in it. But because we must still wage an incessant warfare with the flesh, it shall not be consummated until the fulfilment of the prophecy of Isaiah: ‘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); in other words, when God shall be ‘all in all’ (I Cor. 15:28). It may seem therefore that by the seventh day the Lord delineated to His people the future perfection of His Sabbath in the last day that by continual meditation of the Sabbath, they might throughout their whole lives[!] aspire to this perfection."