The other special Shabbats occur on specific sabbaths before or coinciding with certain Jewish holidays during the year according to a fixed pattern.
It is alternately known as Shabbat Shuvah owing to its being one of the Aseret Yemei Teshuvah (Ten Days of Repentance).
There is an Ashkenazi custom to feed wild birds on this Shabbat, in recognition of their help to Moses in the Desert.
These are four special Sabbaths, each of which derives its name from the additional Torah portion that is read that day.
Deuteronomy 25:17-19 (at the end of Parasha Ki Teitzei), describing the attack on the weakest by Amalek, is recounted.
There is a tradition from the Talmud (understood to be implied in the Megillah itself) that Haman, the antagonist of the Purim story, was descended from Amalek.
Numbers 19:1-22 (the beginning of Parasha Chukat) describes the parah adumah ("red heifer") in the Jewish Temple as part of the manner in which the kohanim and the Jews purified themselves so that they would be ready ("pure") to sacrifice the korban Pesach.
A special maftir, Exodus 12:1-20 (from Parashah Bo) is read, in which the laws of Passover are defined.
It is also called black sabbath due to Isaiah's prophecy of rebuke predicting the destruction of the first temple in the siege of Jerusalem and its status as the saddest shabbat of the year (as opposed to the white sabbath, Shabbat Shuvah, immediately preceding Yom Kippur).
Shabbat Nachamu is traditionally celebrated with singing, dancing, eating, and musical performances that extend into the early hours of the following morning.
It is a custom that women make an extra effort to attend synagogue to hear and recite this prayer.
One of each of the first six parashot of the Book of Exodus are read in the synagogue on Shabbat, typically during the Hebrew months of Tevet and Shevat (around January to February in the civil calendar).
Some people have the custom of fasting (ta'anit) and giving extra tzedakah during this time, and of reciting Selichot and other Kabbalistic prayers and tikkunim.