Rabbi Elazar Hamodai expanded the promise of Sabbath observance far beyond three festivals. Where Rabbi Yehoshua linked Shabbat (the Sabbath) to Pesach (Passover), Shavuot, and Succot, Rabbi Elazar promised six extraordinary rewards to anyone who merits keeping the Sabbath properly.
The six rewards he listed are staggering in scope. First, Eretz Yisrael, the Land of Israel itself. Sabbath observance earns a share in the Holy Land, the territory promised to Abraham and his descendants. Second, the world to come, Olam HaBa (עולם הבא), the eternal life that follows this one. Third, the new world, a renewed creation that God will fashion at the end of days.
Fourth, the kingdom of the house of David. Keeping Shabbat connects a person to the restored Davidic monarchy, the messianic kingdom that will one day rule Israel again. Fifth, the Kehunah, the priesthood. Even those who are not descended from Aaron can earn a spiritual share in the priestly service through Sabbath observance. Sixth, the Leviyah, the Levitical service, the sacred music, gatekeeping, and Temple duties of the tribe of Levi.
Rabbi Elazar grounded all six rewards in Moses' triple repetition of "eat it today" from (Exodus 16:25). The three "todays" each yield a double reward, producing six in total. This teaching from the Mekhilta DeRabbi Yishmael transforms the Sabbath from a day of rest into the single most consequential act of observance in Jewish life. Keep one day holy each week, and God promises you the Land, eternity, a new world, a king, a priesthood, and a place in the Temple service.