The fast of Tammuz
The destruction of Jerusalem, by David Roberts, 1850
Private fasts can be associated with days of joy (an example is the fast of a bride and groom leading up to their wedding) or with days of sadness (such as the fast on the day of a Yahrzeit).
Public fasts involve the whole community – for example, occasions of supplication like the existential day of 7 June, 1967, when no-one could be certain that Israel would survive, and the historical fasts associated with the destruction of the Temple.
Yom Kippur is the only occasion when there is fasting on Shabbat. If a historical fast like 17 Tammuz (“the fast of the fourth month”: Zech. 8:19) is due to fall on Shabbat, it is postponed to the following day. An exception is the Fast of Esther, which is observed on the previous Thursday.
Only Yom Kippur and Tishah B’Av (“the fast of the fifth month”) run from evening to evening. 17 Tammuz and the other fasts are from daybreak to nightfall.
