Two Temples, One Date, and a Deferral This Rule Does Not Model

Tisha B'Av, the ninth of Av, is the Hebrew calendar's most somber fast day, marking, in a tradition recorded in rabbinic sources, the destruction of both the First Temple by Babylon in the sixth century BCE and the Second Temple by Rome in 70 CE, held to have occurred on the same calendar date centuries apart. Jewish tradition has since attached a wider list of catastrophes to the date as well, among them the 1492 expulsion of Jews from Spain, so the day functions as a fixed point around which a longer history of loss is gathered rather than a memorial to one event alone.

The fast runs a full twenty five hours, comparable in severity to Yom Kippur though mournful rather than penitential in tone, and the day's central practice is the public reading of the Book of Lamentations, traditionally chanted in a distinctive mournful melody. One detail worth flagging explicitly is that when the ninth of Av falls on Shabbat, observance is deferred to the tenth, since a public fast of this kind cannot be kept on the Sabbath itself; the underlying date remains the ninth even though the observance itself shifts to accommodate the exception. Alongside the fast, several other customary restrictions accumulate in the weeks leading up to Tisha B'Av in many communities, a period sometimes called the Three Weeks, during which weddings, haircuts and other occasions of ordinary joy are traditionally avoided, treating the fast day itself as the culmination of a lengthening season of mourning rather than an isolated observance.