Yoma, Chapter Two, Mishnah Five
This mishnah teaches how many priests were necessary to offer the two tamid offerings, the one offered in the morning and the one in the evening.
1) The tamid was offered up by nine, ten, eleven or twelve [priests], neither by more, nor by less.
2) [The offering] itself by nine;
3) At the festival [of Sukkot] in the hand of one a flask of water, behold there were ten.
4) In the evening by eleven: [The offering] itself by nine and in the hands of two men were two logs of wood.
5) On Shabbat by eleven: [The offering] itself by nine, in the hands of two men two handfuls of incense for the showbread.
6) And on Shabbat which fell during the festival of Sukkot one man carried in his hand a flask of water.
Section one: This section introduces the rest of the mishnah, using a format which will be easily remembered. It is very typical for mishnayot to open with such formulas.
Section two: In mishnah three we learned that it took nine priests to carry the various parts of the tamid offering up the ramp and then afterwards from the ramp to the altar. This referred to the morning tamid offering. As we shall see below in section four, the evening tamid required two more priests.
Section three: On Sukkot at the morning tamid they would also offer a water libation. We shall learn more about this water libation when we study Tractate Sukkah.
Section four: The evening tamid, offered at dusk, required eleven priests. Nine to carry the offering itself and two to carry about two logs of wood to add to the altars fires. They also added wood in the morning, but in the morning the wood was added by the priest who cleaned out the old ashes (see above mishayot 1-2). This was done before the tamid was offered.
Section five: On Shabbat the morning tamid also required eleven priests. Nine to offer the sacrifice itself and two to carry the incense which was offered every Shabbat in honor of the outgoing showbread (see Leviticus 24:6-7).
Section six: On Shabbat morning during Sukkot they needed the eleven as is the case in a normal Shabbat and one more to carry the flask of water.