Merkaz HaRav Yeshiva marked Simchat Beit HaShoeva, literally "water pouring event", with dancing that went on all night Sunday and continued in the morning. The traditional festivity harkens back to ancient times, when the Holy Temple was standing.
In Temple times, the rejoicing was connected to the libation of water on the Temple altar, which took place during the week of Sukkot. Water would be drawn from the Gihon spring and brought to the Temple. The process was accompanied by dance and song throughout the streets of Jerusalem, and the Talmud says that “he who has not seen Simchat [the Joy of] Beit HaShoevah has not seen rejoicing in his life.”
It was said that there was no yard in Jerusalem that was not illuminated by the Simchat Beit HaShoevah lights, and that the leading Sages danced while juggling burning torches in their hands. Members of the priestly classes – Kohanim and Levites – would play lyres, cymbals, trumpets and other instruments.