In Judaism, Rosh Chodesh or Rosh Hodesh is a minor holiday observed at the beginning of every month in the Hebrew calendar, marked by the birth of a new moon. Rosh Chodesh is observed for either one or two days, depending on whether the previous month contained 29 or 30 days.

Shabbat or the Sabbath, also called Shabbos by Ashkenazim, is Judaism's day of rest on the seventh day of the week—i.e., Saturday. On this day, religious Jews remember the biblical stories describing the creation of the heaven and earth in six days and the redemption from slavery and the Exodus from Egypt, and look forward to a future Messianic Age. Since the Jewish religious calendar counts days from sunset to sunset, Shabbat begins in the evening of what on the civil calendar is Friday.