We now begin chapter 4 of Maseches Taanis, mishnah 1. The mishnah discusses the special occasions on which the kohanim would raise their hands to bless the people, and from its wording we will learn an important inference made by the Gemara.
The words of the mishnah:
"Bishloshah perakim bashanah kohanim nosim es kapeihem arba pe'amim bayom: b'shacharis, b'musaf, u'v'minchah, u'v'ne'ilas she'arim - b'taaniyos, u'v'maamados, u'v'Yom HaKippurim" - on three occasions during the year the kohanim raise their hands four times a day: at Shacharis, at Musaf, at Minchah, and at the closing of the gates - on fast days, at the maamados, and on Yom Kippur.
In other words, three times during the year the kohanim would ascend the duchan - the priestly blessing in which the kohanim bless the congregation - four times in a single day. The four prayers are:
Shacharis.
Musaf.
Minchah.
Ne'ilas she'arim - the prayer we call Ne'ilah, which we recite on Yom Kippur.
And the three occasions in the year are: the fast days (the public fasts we have been studying), the maamados (which we will discuss later in the chapter), and Yom Kippur.
The Gemara's inference:
The Gemara points out that the wording of the mishnah as we have it is not precise, since it implies that fast days and maamados also have a Musaf prayer, which is not the case. The Gemara therefore establishes that our mishnah is a case of "chisurei mechsera" - words are missing from it, and it should be read as follows:
"Bishloshah perakim bashanah kohanim nosim es kapeihem kol zman shemispallelin" - on three occasions in the year the kohanim raise their hands at every prayer, meaning at Shacharis, at Minchah and at Ne'ilah, for on fast days and at the maamados they would also recite the Ne'ilah prayer. "V'yesh bahen arba pe'amim bayom" - and among them there is one that has four times in a single day: Shacharis, Musaf, Minchah and Ne'ilah, and that is Yom Kippur.
It emerges, then, that of the three occasions in the year:
On Yom Kippur - the kohanim bless four times in the day, since it has a Musaf prayer.
On fast days and at the maamados - only three times, since these days have no Musaf prayer.
In summary: in this mishnah we learned that on three occasions in the year - on fast days, at the maamados, and on Yom Kippur - the kohanim raise their hands at every single prayer, including Ne'ilah. The Gemara explained the mishnah by way of "chisurei mechsera", according to which fast days and maamados have three priestly blessings, while Yom Kippur, which has Musaf, has four.
Later in the chapter we will discuss the maamados and what they were.