Rabbi Yonasan Sacks
The Dual Nature of Tisha Ba'av
Although we observe several rabbinic fast days throughout the year, our commemoration of Tisha Ba'av is uniquely stringent. On Tisha Ba'av, like Yom Hakippurim, we begin fasting in the evening and observe all chamishah iyunim.
Tosfos Yeshanim (Megilah 5b) explains that originally Tisha Ba'av was similar to the other rabbinic fasts during which only eating and drinking were forbidden. Indeed, the navi Zechariah (8:9) equates Tisha Ba'av, the tzom hachamishi, with other yearly fasts. Only later, as a separate takanah, Tisha Ba'av was elevated to a ta'anis which parallels Yom Hakippurim.
The Ramban however maintains that initially, all fasts included the chamishah inuyim. Subsequently, however, when the harshness of other fast days were reduced, the stringencies of Tisha Ba'av remained.
The Rambam emphasizes (Peirush Hamishnayos, Maseches Ta'anis) that our observance of Tisha Ba'av reflects two distinct aspects of the day. Tisha Ba'av is not only a ta'anis tzibbur, but also a day of aveilus. Because Tisha Ba'av is a ta'anis tzibbur we refrain from eating and drinking. We sit on the floor and refrain from Torah study to mark the fact that Tisha Ba'av is a day of mourning.
The Minchas Chinuch (Mitzvah 312) suggests that the issur rechitzah, the prohibition to wash, for example, links these two elements. Both an avel as well as someone who observes a taanis tzibbur are forbidden to wash. However, whereas aveilus prohibits one from washing their entire body, taanis tzibbur forbids one from washing a small part of the body as well.
The Minchas Chinuch further suggests that when Tisha Ba'av occurs on Shabbos, although the ta'anis is observed on Sunday, various aspects of avielus apply even on Shabbos.
The Rambam extends another element of Yom Hakippurim to Tisha Ba'av. The Gemara (Yoma 81b) explains that one is obligated to begin Yom Hakippurim early, before sunset. The Torah obligation is determined from, "Veinisem es nafshoseichem betisha bachodesh baerev, " indicating that Yom Hakippurim is to begin on the ninth of Tishrei towards evening. Most rishonim maintain that this mitzvah is not limited to Yom Hakippurim but applies to Shabbos and yom tov as well. The Rambam does not mention the mitzvah of tosefes Shabbos and yom tov in the Perush Hamishnayos; however, he does emphasize the need to begin Tisha Ba'av early, "umosifin michol el hakodesh." According to the Rambam, the mitzvah of tosefes is not a function of kiddush hayom, but rather of taanis tzibbur.
Our commemoration of Tisha Ba'av uniquely binds these aspects of taanis tzibbur and aveilus. May our observance be meorer rachmei shomayim as we await biyas goel tzedek bimhera biyameinu.