In the Jewish calendar, today is 10th Tevet (Asarah B’Tevet), one of the six fasts in the Jewish year. Similar to 9th Av (Tish B’Av) and the 17th Tammuz (Shiva Asar B’Tammuz), it commemorates the events leading up to the destruction of the Holy Temple.
The 10th of Tevet marks the beginning of the Babylonian siege against Jerusalem. Led by their king Nebuchadnezzar, the mighty forces – armed with rich provisions and access to water – surrounded the walled city from every side, and cut off every access point in the surrounding wall.
The huge Greek army waited patiently until the Jews trapped within their city fortress could no longer survive. This siege ultimately prefaced the Babylonians breaking the city wall and destroying the First Temple – two and a half years after their conquest began.
Asarah B’Tevet is unique in that it (along with Yom Kippur) is allowed to observed on Friday, and even on Shabbat. This is because the wording used – and on that day – is only used pertaining to Yom Kippur and 10th Tevet.
It’s considered a “minor” fast: eating and drinking alone are only forbidden from dawn until dusk, and there are no other prohibitions. This is a sharp contrast with Yom Kippur’s list of forbidden behaviors, and the strict laws and longer hours of Tisha B’Av.
It’s minor status transcends its “similar to Yom Kippur” status, however: one who is even slightly sick is relieved from fasting, as are pregnant and nursing parents.
Tzom Kal (an easy fast) to those fasting today!