Zechariah 7:3 “…Should I weep in the fifth month and fast as I have done for so many years?”
Tisha B’Av, an annual fast day in Judaism, is named for the ninth day (Tisha) of the month of Av in the Hebrew calendar.
The fast commemorates the destruction of both the First Temple and Second Temple in Jerusalem, which occurred about 655 years apart, but on the same Hebrew calendar date, the ninth day of Av.
These two events were so tragic that the ancient rabbis declared the anniversary of the Temples’ destruction a day of mourning. This is the origin of Tisha B’Av.
Many other significant calamities occurred to the Jewish people on the 9th of Av.