Tammuz is a fast day. Since the actual date falls on a Shabbat, and we do not fast or mourn on a Shabbat it is postponed until the following day.
We fast both food and drink from dawn to sunset- in our locale from 5:46 am to about 8:30pm or 3 stars.
The fast of the 17th of the Hebrew month of Tammuz, known as Shiva Asar B'Tammuz, is the start of a three-week mourning period for the destruction of Jerusalem and the two Holy Temples. It ends on Tisha b’Av or with the fast of the 9th of Av, this year on July 29th.
The fast actually commemorates five tragic events that occurred on this date:
- Moses broke the tablets when he saw the Jewish people worshipping the Golden Calf.
- During the Babylonian siege of Jerusalem, the Jews were forced to cease offering the daily sacrifices due to the lack of sheep.
- Apostomos burned the holy Torah.
- An idol was placed in the Holy Temple.
- The walls of Jerusalem were breached by the Romans, in 69 CE, after a lengthy siege. (Three weeks later, after the Jews put up a valiant struggle, the Romans destroyed the second Holy Temple on the 9th of Av.)
The Jerusalem Talmud maintains that this is also the date when the Babylonians breached the walls of Jerusalem on their way to destroying the first Temple.
The Torah is read during the morning and afternoon prayers. The reading the same for both morning and afternoon is Exodus 32:11-14 and 34:1-10, which discusses the aftermath of the Golden Calf incident, how Moses successfully interceded on the Israelites' behalf and attained forgiveness for their sin. After the afternoon Torah reading, the special fast-day haftarah, Isaiah 55:6-56:8, is read.
The sages explain: "Every generation for which the Temple is not rebuilt, it is as though the Temple was destroyed for that generation." A fast day is not only a sad day but, an opportune day. It's a day when we are empowered to fix the cause of that destruction, by turning our hearts back to G-d, praying that our long exile will be ended and we will find ourselves living in messianic times-may that be very soon.