As we have learned (daf 107), this perek focuses on the prohibition against bringing sacrifices outside of the Temple. In fact, not only are sacrifices forbidden outside of the Temple, but all services unique to the Temple cannot be performed outside of it. In the Mishna on today’s daf Rabbi Elazar teaches that someone who pours a water libation on the holiday of Sukkot outside of the Temple is liable for performing a Temple service inappropriately.
The water libation service is described in detail in Massekhet Sukka (see daf 48), where the Mishna describes the nisukh ha-mayim. Water was brought from the Shiloaḥ spring up to the Temple with great fanfare. The kohen would take the jug of water, walk up the ramp to the altar and turn left, where there were two bowls – sefalim– that drained into the foundation of the Temple. The bowls were for the nisukh ha-mayim on Sukkot and for the nisukh ha-yayin, the wine libation that accompanied many of the sacrifices. The kohen was instructed to raise up his hand so it would be clear that he was doing the avoda properly. This was instituted because a kohen once poured the water on his feet instead of on the altar, and the enraged crowd pelted him with the etrogim that they were holding in their hands.
Although Rabbi Elazar’s position is first identified as following Rabbi Akiva who derives the service of the water libation from passages in the Torah (Bamidbar 29:31), the Gemara concludes that this mitzva is a halakha le-Moshe mi-Sinai – an oral tradition received by Moses on Mount Sinai. In his Commentary to the Mishna, the Rambam suggests that the halakha will be different depending on whether the source for this mitzva is actually in the Torah or if it is an oral tradition from Moshe. While many of the commentaries object to this distinction, arguing that both are considered biblical, it appears that the Rambam follows the approach of the Talmud Yerushalmi (Sanhedrin 11:4) that distinguishes between them, and understands that halakha le-Moshe mi-Sinai is similar, on some level, to divrei soferim – the teaching of the Rabbis.