Leviticus 23:35

on the first day shall be an holy convocation. — At daybreak of this day one of the priests, accompanied by a jubilant procession and a band of music, went with a golden pitcher to the pool of Siloam, and having filled it with water, returned with it to the Temple in time to join his brother-priests in the morning sacrifices. He entered from the south through the water-gate, when he was welcomed by three blasts of the trumpets. He then ascended the steps of the altar with another priest, who carried a pitcher of wine for the drink offering. The two priests turned to the left of the altar, where two silver basins were fixed with holes at the bottom, and simultaneously poured into their respective basins the water and the wine in such a manner that both were emptied at the same time upon the base of the altar. This ceremony of drawing the water was repeated every morning during the seven days of the festival. Another jubilant multitude, who went outside Jerusalem at the same time to gather willows, now returned. With great rejoicings and amidst blasts of trumpets they carried the willows into the Temple, and placed them at the altar in such a manner that their tops overhung and formed a kind of canopy.

Ye shall do no servile work therein. — For the difference between servile and necessary work see Leviticus 23:7.