Today is the ninth of Kislev, the Yom Hillula of the Mitteler Rebbe. Why is it so important to mark a Yom Hillula of one of the Rebbeim? The Rebbe once said of this day:
In a letter, my father-in-law, the [Previous] Rebbe, explains the tremendous importance of utilizing the Yom Hillula of a tzaddik by studying Torah and taking part in a farbrengen. In this letter he describes the Yom Hillula of 9 Kislev, 5657 ... at which the Rebbe Rashab said: “Observing the tzaddik’s Yom Hillula by studying his teachings and by holding a farbrengen is the pidyon nefesh that we give him.”
It is easy to imagine that if there were an opportunity now to go to the Mitteler Rebbe and give him a pidyon nefesh, everyone would surely rush to do so.
Based on the above, we now indeed have the opportunity to hand a pidyon nefesh to the Mitteler Rebbe through the farbrengen that we are holding now, and by studying his teachings after the farbrengen, when everyone returns home. One should study a teaching from one of the works of the Mitteler Rebbe, whose Yom Hillula we are marking.
Moreover, this brings that tzaddik to davven on one’s behalf, just as a pidyon nefesh is a request for the tzaddik to davven on one’s behalf.