Mussaf

Mussaf (Hebrew: מוּסָף, also spelled Musaf or Musof) is a Jewish prayer service that is recited on Shabbat, Jewish holidays, Chol Hamoed, and Rosh Chodesh in addition to the three other services religious Jews recite daily: Shacharit (morning), Mincha (afternoon), and Maariv (evening). It is traditionally combined with Shacharit when recited. In contemporary Hebrew, the word may also signify a newspaper supplement.

During the days of the Temple in Jerusalem, additional sacrificial offerings were given on Shabbat, festival, days Rosh Chodesh, and Chol Hamoed; in the absence of sacrifices, Mussaf were likely instituted between the destruction of the Second Temple in 70 CE and the end of the Mishnaic period.

Mussaf refers to both the complete service—which includes the Amidah and all other Jewish prayers recited following Shacharit —and the Amidah that is recited in Mussaf itself. The main addition is a fourth blessing of the Amidah, especially for the noted days. The time permitted for the recitation of Mussaf extends until the seventh halakhic hour of the day, which divides the day into twelve-hour segments. It is recommended to begin Mussaf before 6.5 halakhic hours, as doing so helps to avoid uncertainty regarding whether to recite Mussaf or Mincha first. If Mussaf is not recited by this time, it remains permissible to recite it for the remainder of the day; however, a person who intentionally delays this is referred to as a "sinner" by Rabbis in tractate Berakhot 28a of the Talmud.

The Priestly Blessing is said during a congregational hazzan's repetition of the Amidah. In the Eastern Ashkenazic rite outside the land of Israel, the Mussaf Amidah of major Jewish holidays is the only time the Priestly Blessing is said.