Is Shabbat the holiest of all Jewish observances, superseding any other of the Jewish year?
AskTheRabbi.org answered:
No, it is the second holiest time of the year. The holiest day of the year is actually Yom Kippur - the Day of Atonement - which is called Shabbat Shabbaton by the Torah and is the only fast day of the year that we fast on Shabbat if they coincide.
