The Nine Days of Av are a time of commemoration and spiritual observance in Judaism during the first nine days of the Jewish month of Av (corresponding to July/August). The Nine Days begin on Rosh Chodesh Av ("First of Av") and culminates on the public fast day of Tisha B'Av ("Ninth of Av").
The Nine Days are part of a larger period of time known as The Three Weeks, which begin with the public fast day of the Seventeenth of Tammuz—commemorated in Judaism for the time when the forces of Nebuchadnezzar of Babylonia broke through the defensive walls surrounding Jerusalem, generally accepted as happening in 586 BCE—and end with the public fast day of Tisha B'Av—when, according to the Mishna, the Babylonians destroyed the First Temple in 597 BCE and when the Second Temple was destroyed by the Romans in 70 CE. During the entire Three Weeks, certain activities are abstained by Jews observing Jewish law in order to commemorate, remember and inspire mourning over destruction of the Temple.
The Talmud says, "When the month of Av begins, we [i.e. Jews] reduce our joy." The Nine Days inaugurates an even greater level of communal and personal mourning in recognition of the many tragedies and calamities that befell the Jewish people at this time. The Nine Days are considered an inauspicious time even in our day and age. The Talmud states that all who mourn the destruction of Jerusalem will merit to rejoice in its rebuilding. The Sages also teach that the Jewish Messiah will be born on Tisha B'Av. It is that promise of redemption which nevertheless makes this period one of hope and anticipation in Judaism.
Mourning observances
Levels of mourning
The mourning observances during the Three Weeks are divided into four levels, increasing in intensity: Engagements are permitted. The custom is also to avoid saying the blessing over a new fruit on a weekday (one may do so on Shabbat), and making a major purchase such as a new home or car.
During the Nine Days, these additional activities are forbidden by Jewish law because they bring joy:
Many kosher meat restaurants alter their menus during The Nine Days, replacing meat and chicken dishes with fish and vegetarian options in order to remain open while the meat prohibition is in place.
Children, pregnant or nursing women, and old or sick people who must eat meat for health reasons are allowed to do so. It is advisable, however, for them to eat poultry or meat derivatives.
Children
Children under the age of Bar and Bat Mitzvah are generally included in the lighter mourning practices as training for mitzvah-observance. Thus, they will also refrain from listening to music or getting haircuts during the entire Three Weeks. However, young children are allowed to wear freshly washed clothes, and parents are allowed to launder those clothes for their children during the Nine Days. On Tisha B'Av itself, campers gather to listen to the traditional reading of the Book of Lamentations and engage in creative projects that express the themes of the day.
Exceptions
On Shabbat, all forms of mourning are suspended. Therefore, observant Jews eat meat at their Shabbat meals and drink wine or grape juice for Kiddush as usual. Similarly, while during the rest of the week one cannot wear freshly laundered clothes, on Shabbat, this is allowed.
The last Lubavitcher Rebbe, Rabbi Menachem Mendel Schneersohn, requested that a siyum of a Talmudic tractate should be held every day of The Nine Days. Chabad now broadcasts the completion of tractates on its website.
An exception to the prohibition against new construction is made in the case of a building constructed for a mitzvah. Thus, a synagogue, yeshiva or mikveh may be constructed or decorated during the Nine Days.
The Seudah HaMafseket resembles the meal of a mourner. The custom is to eat cold, hard-boiled eggs or lentils with bread and water. Only one cooked food may be eaten. The bread is dipped in ashes. Those who are eating sit on the ground or on low chairs, as they will during the night and morning of Tisha B'Av, and do not converse with each other.