The Rebbe, in his classic work Hayom Yom, has an entry for 22 Nissan, which in the Diaspora is Acharon shel Pesach (the Last Day of Pesach). In Eretz Yisrael, Acharon shel Pesach is a day earlier, on the seventh day of Pesach which this year, outside Israel, falls out on Shabbos, April 23.
The Rebbe writes that on Acharon shel Pesach, the Baal Shem Tov would eat three seudos (meals), the third being the feast of Moshiach. Why is this meal called the meal of Moshiach? Because on the last day of Pesach, the radiance of Moshiach is openly revealed.
The Rebbe continues that in the year 5666 (1906), the talmidim of the yeshiva in the town of Lubavitch ate the Acharon Shel Pesach meal in the study hall. At that time, there were 310 students sitting at 18 tables. That year, the Rebbe Rashab (the Previous Rebbe’s father) joined the talmidim for the third meal on Acharon shel Pesach and instructed that each of them receive four cups of wine from the yeshiva. He declared, “This is Moshiach’s seudah.”
Now, there could be a Jew who will come and ask a question: Why is Moshiach’s seudah on Acharon shel Pesach; why not on any other day?
The response is that whether he’s an Ashkenazi or a Sefardi, comes from Chassidic or Litvish background, whether he comes from Russia, Poland, Germany, the Middle or Far East, Hungary, or Romania – the Haftarah he reads on Acharon shel Pesach is the Haftarah of Moshiach, a Haftarah that discusses the coming of Moshiach at length.
What does it say there? “And there shall come forth a staff from the shoots of Yishai. And the twig shall grow forth out of his roots. And the spirit of G-d will rest upon him, a spirit of wisdom and understanding, a spirit of counsel and courage, a spirit of knowledge and fear of G-d….”
A few verses later come the famous phrase that many of us know: “And the wolf shall dwell with the lamb, and the leopard will lie down with the kid… and a small child will lead them.”
Continuing later in the same Haftarah: “He will assemble the dispersed of Israel. And He will gather together the scattered of Yehuda from all the four corners of the world.”
Every Jew, regardless of his affiliation, reads the same Haftarah – all about Moshiach, on Acharon Shel Pesach.
This answers the question as to why the Baal Shem Tov specifically ate the seudah of Moshiach on Acharon shel Pesach. The custom of having this seudah, as we learned, was started by the Bal Shem Tov. The Rebbe Rashab added that the talmidim in the Lubavitch yeshiva of Tomchei Temimim be given four cups of wine.
And the Rebbe in our generation added that this is not only for students of Tomchei Temimim; this is for every Jew. Every Jew should participate in a Moshiach seudah on Acharon shel Pesach.
Moreover, the Rebbe said that there is a tradition that on Acharon shel Pesach there is also a “Moshiach tantz” – a “Moshiach Dance.” The Rebbe said that we should interpret that tradition in a manner most advantageous to us – that the “Moshiach Dance” means that Moshiach is going to dance together with all participants.
So when Jews – in any part of the world – get together on Acharon Shel Pesach for the seudah of Moshiach and they dance the “Moshiach Dance” – Moshiach dances with them.
The seudas Moshiach has a very simple menu: matzah, salt, water, and wine.
At the seudah, Jews sing and dance the “Moshiach Dance” in anticipation of Moshiach’s coming. By doing that we are telling Moshiach that we are already celebrating his arrival.