The last nine days of the Three Weeks, the mournful period before Tisha B’Av, start on the first of the Jewish month of Av and occupy a special status. During the nine days, foods traditionally associated with joy, such as wine and meat, are forbidden, except on Shabbat. Bathing, beyond what is absolutely necessary, is prohibited, as is doing laundry, and buying or wearing new clothes.
The nine days culminate in the fast of Tisha B’Av, the Ninth of Av, a day that is spent entirely in mourning —by fasting, praying, sitting on stools instead of chairs and reading the Book of Lamentations. The Mishnah, in Masekhet Taanit 29b, decrees that these additional restrictions are only valid in “shavua she-hal bo,” or the week that Tisha B’Av occurs. Many Jews observe the restrictions only within this period.