It was shortly after the conclusion of Shabbat on December 8th, 1951. The Rebbe went outside “770” (the central Chabad-Lubavitch synagogue located in Brooklyn at 770 Eastern Parkway, is commonly referred to as “770”) to recite the Kiddush Levana prayer. (Kiddush Levana, or “sanctification of the moon,” is traditionally recited outside while still wearing one’s Shabbat clothing, and can only be performed if the moon is visible.)
Obscured by clouds, the moon was nowhere to be seen. Unable to recite the prayer, the Rebbe went back inside. Back inside the synagogue, he turned to his chassidim, and told the following story:
“Once, the Rebbe Rashab (the 5th Rebbe), went outside with some of his chassidim to recite Kiddush Levana; the sky was covered withclouds. He recounted that one time, in the court of Reb Meir of Premishlan (1783-1850), the tzaddik was unable to recite Kiddush Levana, as the moon was not visible due to thick cloud cover.
“Reb Meir remarked that he was curious as to how the Jewish people recited Kiddush Levana while traveling in the desert for 40 years. After all, the Torah tells us that we were surrounded by the Clouds of Glory even from above and were therefore unable to see the moon!
“The answer, Reb Meir said, was certainly that Moses would simply wave a handkerchief — a mach getohn mitn tichel — and the cloudswould scatter. As Reb Meir demonstrated how Moses waved a kerchief, the sky cleared up above him.
“When the Rebbe Rashab told this story, he too, demonstrated the waving motion with his handkerchief; the clouds immediately dispersed and the moon became visible.
“If anyone is here today that can do something like that,” the Rebbe concluded, “perhaps we will be able to recite Kiddush Levana.”
Someone in the crowd said, “The Rebbe can do it!”
Smiling, the Rebbe responded, “It’s sufficient that I told the story…”
The Rebbe then announced ich kum bald tzurik, he would return shortly, and he went to his mother’s home nearby to recite the havdalaprayer for her. When he returned to “770” a short while later, the sky was clear and everyone recited Kiddush Levana.