At the end of the Torah reading of Pinchas,1 we read about the additional sacrifices that were offered in the Temple on special days. These additional sacrifices are called musaf (in the singular) or musafin (in the plural), meaning "additions," and they were offered on Shabbat, Rosh Chodesh, Passover, Shavuot, Rosh Hashanah, Yom Kippur, and Sukkot, as well as on the intermediate days (Chol Hamoed) of Passover and Sukkot.

At the beginning of the Second Temple Era, when the sages instituted the daily prayers, they included one prayer for each of the regular communal sacrifices.2 They also instituted the Musaf prayer to be recited on any day when the musaf sacrifice was to be offered.

The unique Musaf blessing includes a prayer for the restoration of the Temple, when we will again be able to offer the special sacrificesThe Musaf prayer is an amidah (standing prayer) which starts and concludes with the standard introductory amidah blessings (three in the beginning and three in the end). Sandwiched between these blessings is the unique Musaf blessing that includes a prayer for the restoration of the Holy Temple, when we will once again be able to offer the special sacrifices of that day, and also thanks G‑d for the sanctity of the holiday and quotes Torah verses about the particular sacrifices of that day.3

The cantor's repetition of Musaf includes the Kedushah, a call-and-response prayer recited by the cantor and congregation during all prayers that features the cantor's repetition of the amidah. On Shabbat and festivals, the Musaf Kedushah includes the first verse of Shema as well as its last three words ("ani Adonai Elohechem"). The custom originates from the following story:4

There was a Persian king in the third century whose name was Yuzgadar. He passed a decree forbidding the Jews to recite the Shema when they prayed. In response, the sages of the time inserted a surreptitious reading of the Shema, by the cantor, into the Kedushah of all the prayers, so that the children would not forget it altogether. In addition, they prayed that the decree be averted.

Their prayers were answered, and King Yuzgadar was swallowed by a snake in his bedroom at midday. To memorialize the miracle, the sages kept the Shema in the Musaf Kedushah (as opposed to other prayers that anyhow incorporate the Shema).

On the festival days of Passover, Shavuot, Rosh Hashanah, Yom Kippur, and Sukkot, the cantor's repetition of Musaf includes the Priestly Blessing5 (even in those communities and circles where this blessing is not administered on a daily or weekly basis. Click here for more information on this subject).

Following are some of the laws of the Musaf prayer.

  1. Ideally the Musaf should be recited before the end of the seventh "seasonal hour" of the day,6 because the musaf sacrifices were supposed to have been brought by that time.7 If one missed this time frame, however, one may still pray Musaf until sunset.
  2. The usual order of the prayers is Musaf and then Minchah (the daily afternoon service). If it is still earlier than a seasonal half-hour after midday (which marks the earliest time one may pray Minchah) this is not an issue, as in any case it is still too early to pray Minchah.
  3. On certain festival days, the cantor's repetition of Musaf includes the Priestly BlessingIn some cases, this order should be reversed. This is because of the principle known as tadir veshe'eno tadir, tadir kodem ("if one must choose between doing two mitzvot, one should first do the one that is more regular"). Minchah is a daily – regular – prayer, and so it sometimes takes precedence over Musaf, which is only recited on special days. There are two scenarios in which the order should be reversed:
    a) If one is praying after Minchah Ketanah.
    b) If one is praying before Minchah Ketanah, but needs to pray both Minchah and Musaf at once.
    In these two scenarios one should pray Mincha first, and then Musaf. If one is praying before Minchah Ketanah and one does not need to pray Minchah right away, one should pray Musaf first, take a break, and then pray Minchah later.
    This all applies only if one is praying alone. If one is praying with a minyan, the minyan always prays Musaf first—no matter the lateness of the hour. 8
  4. If one neglected to pray Musaf and night has fallen, one can no longer make it up.9 This is unlike the regular daily prayers, which can be made up in certain circumstances10 (click here for more on this topic).
  5. One who mistakenly recites the regular amidah in the place of Musaf has not fulfilled his obligation and must pray again.11
  6. One who prays Musaf before Shacharit (the morning prayer) has fulfilled his obligation, but one should not choose to do this in the first place.12
  7. If one prays Musaf while the minyan is praying Shacharit or Minchah, or vice versa, he is not fulfilling the mitzvah of praying with a minyan.13
  8. It is inappropriate to be wearing our own crown while praising G‑d for His...It is forbidden to have a full meal before Musaf, but it is permitted to have a snack. A snack is defined as fruit or other non-grain-based food. It is also permitted to eat grain-based foods in quantities less than the volume of an egg.14 (Obviously, this should not be done in a way that interferes with hearing the Torah or Haftorah reading, or praying Musaf with a minyan.)
  9. On Shabbat or Yom Tov, if one wishes to eat before Musaf, one must make Kiddush before partaking of any food.15
  10. The Mishnah Berurah16 rules that one who has no wine for Kiddush and is very weak may have a snack before Musaf even without hearing Kiddush.
  11. On Rosh Chodesh, we take off our tefillin before reciting Musaf.17 This is because the Musaf prayer includes Kedushah, which begins with the word keter, meaning "crown."18 It is inappropriate to be wearing our own crown – the tefillin – while praising G‑d for His crown.19
  12. Those who pray Nusach Ashkenaz do not say the word keter in Kedushah, but they also remove their tefillin for Musaf. This is because the Musaf prayer invokes the sanctity of Rosh Chodesh, which is like a festival. Since we do not wear tefillin on a festival, we do not wear tefillin while praying Musaf either.20