"That I, the Lord, sanctify you" — the Mekhilta interprets this as referring to the world to come. The sanctity that God bestows upon Israel through Sabbath observance is a foretaste of the sanctity they will experience in the future world.
The connection is explicit: the sanctity of the Sabbath in this world is of the same kind as the sanctity of the world to come. The two are not merely analogous — they are the same quality of holiness experienced in different settings. When you observe the Sabbath, you are briefly inhabiting the world to come.
The Mekhilta supports this with (Psalms 92:1): "A psalm, a song for the day of Sabbath." The rabbis read this not merely as a psalm composed for the Sabbath but as "a psalm for the world which is all Sabbath." The world to come is described as an eternal Sabbath — a state of permanent rest, permanent sanctity, permanent closeness to God.
This teaching gives the Sabbath a cosmic dimension. It is not merely a weekly day of rest. It is a portal. Every Sabbath, for twenty-five hours, the Jewish people step out of ordinary time and into the quality of existence that will characterize the messianic age. The rest of the week belongs to this world. The Sabbath belongs to the next. And the psalm that is sung on Saturday is really the anthem of eternity.