The Sabbath before the *New Moon, following the reading of the haftarah, the reader leads the congregation in announcing and blessing the coming month. This custom was introduced by the geonim, and its main purpose was to make a public pronouncement of the exact day(s) on which the New Moon will fall (Maḥzor Vitry, ed. by. S. Hurwitz (19232), 173; Abudarham, Seder Rosh Ḥodesh, ed. Jerusalem (1959), 193). It is possible that this practice was based upon the statement of R. *Yosef, that he did not pray the Musaf service (on the Sabbath before the New Moon) until he knew exactly when the New Moon was to occur (TJ, Sanh. 5:3, 22d; Arukh ha-Shulḥan, OḤ 417:8). The announcement is made after a special prayer for the house of Israel, and in the Ashkenazi rite begins: "He Who wrought miracles for our fathers, and redeemed them from slavery into freedom, may He speedily redeem us and gather our exiles from the four corners of the earth, even all Israel united in fellowship; and let us say, Amen." The exact time of the molad (see *Calendar) is then announced and the reader proclaims the day(s) of the week on which the first day of the coming month falls; and the blessing concludes with the prayer that the New Moon be for life, peace, gladness, salvation, and consolation for the house of Israel (Hertz, Prayer, 510). Prior to the proclamation of the New Moon, the Ashkenazi ritual contains an introductory prayer, Yehi Raẓon, which is substantially the private petition recited daily by Rav upon the completion of the Amidah (Ber. 16b). In order to adjust this prayer to the occasion, the sentence "to renew unto us this coming month for good and for blessing" was inserted (Hertz, Prayer, 508). This introductory prayer was first recited in the Polish ritual during the first part of the 18th century. It then gradually spread to all Ashkenazi rituals. In some rites the words "bi-zekhut tefillat Rav" ("by the merit of the prayer of Rav") appear at the end of the prayer. It has been suggested that this is a mistake for a marginal note which originally read berakhot, tefillat Rav ("blessing [see Tractate Berakhot] the prayer of Rav") to indicate the source and authorship of the prayer. These words were later erroneously incorporated in the liturgy, berakhot being changed to bi-zekhut. A further mistake in some rites changed Rav to rabbim making it end "by the merit of congregational prayer" (E. Munk, The World of Prayer, 2:49). Many Sephardi and Oriental rituals contain introductory prayers for the ingathering of the exiles and the well-being of the rabbis (cf. Abudarham, loc. cit.). It became customary to recite the announcement of the New Moon while standing, in remembrance of the original sanctification of the New Moon by the bet din in Jerusalem, which was done when standing (Magen Avraham to Sh. Ar., OḤ 417:1). It is also customary for the reader to hold the Torah scroll while reciting this prayer. The Sabbath on which the New Moon is announced is popularly known as Shabbat Mevarekhim ("the Sabbath of the Blessing"), or the Sabbath which contains "Rosh Ḥodesh bentshn." A special sermon in honor of the event is preached in some communities. The New Moon of *Tishri is not blessed in advance since it is also Rosh Ha-Shanah and everyone knows when it will occur (Mishnah Berurah, Sha'ar ha-Ẓiyyun, 417:1, no. 2).
Abrahams, Companion, clxi; Elbogen, Gottesdienst, 123f.; Idelsohn, Liturgy, 141; E. Levy, Yesodot ha-Tefillah (19522), 206.