פירוש על סוכה 5:1

החליל – many kinds of musical instruments were there, and by the name of the flute, as its sound is heard more than the others, all of them are called by its name.

Introduction The first four mishnayot of the final chapter of Sukkah are about a Sukkot ritual called “Simchat Bet Hashoevah”, which is usually translated as the “Celebration of the Water-Drawing.” The water-drawing refers to the drawing of the water from the Shiloah in order to perform the water-libation, described above in chapter four. At the end of the all-night Simchat Bet Hashoevah ceremony, early in the morning, they would leave the Temple, go down to the Shiloah and draw the water. It seems that the function of the ceremony was twofold. First of all it highlighted the importance of the water-libation, which as we saw before, was controversial. Secondly, it allowed non-priests a chance to participate in the Sukkot ritual in the Temple. This seems to be one of the major differences between the Pharisees and Sadducees the former encouraged the participation of non-priests in Temple ritual as much as was possible, whereas the Sadducees seemed to have abhorred it.

חמשה וששה – sometimes five [days] and sometimes six [days]. If the first day of the Festival [of Sukkot] occurs on Shabbat, the flute [is sounded] for six [days]; if it (i.e., the first day of the Festival of Sukkot) falls on the other days of the week, the flute [is sounded for] five days, because it does not supersede neither the Sabbath nor the Holy Days [of the Festival].

The flute was for five or six days. This refers to the flute at the Bet Hashoevah [the place of the water-drawing] which does not override Shabbat or the festival day. The mishnah refers to a flute that was played during the Simchat Bet Hashoevah. This celebration would only take place on five or six days because it did not override Shabbat or the festival day. So if the first day of Sukkot and Shabbat coincided, then it would happen for six days; if not for only five. Interestingly, in the descriptions of the Bet Hashoevah that follow, the flute is no longer present. I do not have a good answer for this absence.

שמחת בית השואבה – because all of this rejoicing is on the drawing of waters of libation, they called it the Rejoicing of the House of Drawing on account of (Isaiah 12:5): “Joyfully shall you draw water [from the fountains of triumph].”

They said: he who has not seen the Simchat Bet Hashoevah has never seen rejoicing in his life. The Simchat Bet Hashoevah was supposed to have been the most joyous, celebratory occasion in the Jewish calendar. Indeed, to this day in our tefillot we call Sukkot “the time of our rejoicing (z’man simchatenu)”.