Halakha Bilangan 28:11: Mishneh Torah, Prayer and the Priestly Blessing, Mishneh Torah, Positive Mitzvot, Sefer HaChinukh & Shulchan Arukh, Orach Chayim

On New Moons and on the intermediate days of the festivals, the nineteen blessings are recited for the evening, morning and afternoon services, as on ordinary days; and the prayer beginning, "O our God and God of our fathers, may our remembrance rise, come, etc." is incorporated in the blessing referring to the restoration of the ancient service. The additional service on the intermediate days of the festivals is the same as on the feast itself. On New Moons, one recites for the additional service, the first three and the last three blessings (common to all services) and an intermediate blessing having reference to the additional sacrifice prescribed for the New Moons, and concludes it with the formula, "Who sanctifiest Israel and the new moons."

On the first day of each month, the person first called to the reading of the Law reads three verses from the section beginning Tzav (Numbers 28:1-8). The second person called to the Law repeats the third verse already read by the person called before him and adds the two following verses, so as to leave three verses to the end of the section. The third person called to the Law reads these three verses and also the next section beginning Uveyom Hashabbath (ibid. 28:9-10). The fourth person called to the Law reads the section beginning Uvrashé Chodshechem (ibid. 28:11-15). When the first of the month falls on a Sabbath, two scrolls of the Law are taken out during the morning service. In the first, the portion for the week is read; and in the second, the one who completes the reading reads Uverashé Chodshechem (Numbers 28:11-15). The person who reads the lesson from the Prophets is the one who reads the section concerning the New Moon. The lesson from the Prophets is that section which concludes, "And it shall come to pass that month by month etc." (Isaiah 66:23). When the first of Ab falls on a Sabbath, the lesson from the prophets is the section containing the verses, "Your new moons and your festivals my soul hateth" (ibid. 1:14). When the first day of the month falls on the first day of the week the lesson from the prophets on the preceding Sabbath day is the section beginning, "And Jonathan said unto him; tomorrow is New Moon" (I Samuel 20:18-42).

To offer up an additional sacrifice every New Moon, as it is said, “And in the beginning of your months ye shall offer up….” (Num. 28:11).