This niggun is originally from Jerusalem to the words "Mosai Yiboneh Hamikdosh"
In one of his epistles the Ba'al Shem Tov writes that when his soul ascended to heaven in the year 5507, he approached the palace of Moshiach and inquired of him, Eimosai Ko'ose Mar, "When will the Moshiach come?" The answer of the Moshiach was: "I will come only when your (The Ba'al Shem Tov's) wells of Torah will overflow to the outside." Thus we are taught that the propagation of the Chassidic teachings and customs is a prerequisite and necessary prelude to the coming of the Moshiach. The Lubavitcher Chassidim have adapted a well-known melody to perpetuate the inquiry of the Ba'al Shem Tov and the reply of the Moshiach. This melody is sung frequently in great ecstasy at Chassidic gatherings.