Mishnayos Megillah Perek 3 Mishnah 6

On each day of Hanukkah they read selections from the portion of the dedication of the altar by the tribal princes (Numbers 7). On Purim they read the portion of “And Amalek came” (Exodus 17:8–16). On the New Moon they read the portion of “And in the beginnings of your months” (Numbers 28:11–15). And in the non-priestly watches they read the act of Creation (Genesis 1:1–2:3). The Jewish people were divided into twenty-four watches. Each week, it would be the turn of a different watch to send representatives to Jerusalem to be present in the Temple to witness the sacrificial service. Those remaining behind would fast during the week, from Monday to Thursday, offer special prayers, and read the account of Creation from the Torah. On fast days, they read the portion of blessings and curses (Leviticus, chapter 26). One should not interrupt the reading of the curses by having two different people read them. Rather, one person reads all of them. On Mondays, and on Thursdays, and on Shabbat during the afternoon service, they read in accordance with the regular weekly order, i.e., they proceed to read the first section of the Torah portion that follows the portion that was read on the previous Shabbat morning. However, these readings are not counted as a progression in the reckoning of reading the Torah portions, i.e., they do not proceed on Monday to read the section that immediately follows the section read on Shabbat during the afternoon, and then the following section on Thursday. Rather, until the reading on the following Shabbat morning, they return to and read the same first section of the Torah portion that follows the portion that was read on the previous Shabbat morning. On Festivals and holidays, they read a portion relating to the character of the day, as it is stated: “And Moses declared to the children of Israel the appointed seasons of the Lord” (Leviticus 23:44), which indicates that part of the mitzva of the Festivals is that the people should read the portion relating to them, each one in its appointed time.