The Baal Shem Tov established a custom to eat a third meal on the last day of Passover. This meal is known as “Moshiach’s Meal,” for on this day Moshiach’s radiance is revealed. This revelation foreshadows the Redemption.
It takes place specifically on the last day of Passover, for this is a day which is added only in the Diaspora. The essence of the added day is that in the Diaspora and in the time of exile, the Jewish people transform 24 mundane hours into a day of holiness. On the last day of Passover this means transforming them into a festival of freedom and redemption. And this process of transformation is the essence of the imminent Redemption - converting the very exile itself into redemption, so that G-dliness is revealed even at the very lowest levels of creation.
(Likutei Sichot)
