Hilkhot Assara b’Tevet 5776
Rabbi David Pardo
10th of Tevet
The 10th of Tevet traditionally commemorates the beginning of the siege of Jerusalem by Nebuchadnezzar, a siege that lasted 2½ years and was cut short by raging internal politics. In that sense, it is an unlike the other components of the Temple-mourning fast-cycle (Tzom Gedalia, 17th of Tammuz, and 9th of Av) because unlike those days, where the state of affairs seemed to be sealed, the 10th of Tevet mourns an avertable disaster. This thought alone is worthy of meditation.
Nearly two generations ago, the Chief Rabbinate of Israel declared this day to be the communal day for reciting kaddish for martyrs of the Holocaust whose date of death was unknown. Especially in Israel, this date has acquired a dual significance, being strongly associated with the Holocaust for many. For a haunting sicha delivered on this day, please take in the words of Rav Amital zt”l: http://etzion.org.il/en/kadish-martyrs-holocaust
To commemorate these events we fast from dawn (alot ha-shachar) until nighttime (tzeit ha-kochavim). This arrangement is known colloquially as a “half-day fast.” If you intend to wake up early to eat, you must stipulate your intentions before you go to sleep, and you must finish eating before alot ha-shachar in your locale.
The fast precludes all types of eating, including tasting foods. However, some authorities permitted people who experience great discomfort to wash their mouth out with caution, thus most modern authorities allow brushing teeth (just don’t swallow any of it).
The 17th of Tammuz is considered a minor fast – bathing and wearing leather shoes is permitted.
Given that the fast is considered “minor,” those who are seriously ill or chronically ill may be exempt. Please consult a competent halakhic authority to discuss your situation. Pregnant and nursing women are exempt. If you are taking important medication, such as antibiotics: if you can do so without water, then do that, otherwise, mix something unpleasant (like mouthwash) into the water before using it to wash down your pill. Those who are not fasting for medical reasons should limit their food to nutrition and may not indulge or eat to excess.
Please consult myzmanim.com or ou.org/calendar for the correct start and end time of the fast in your locale.
We make the same additions to davening as we do on other fast days throughout the year. In shaharit we recite selichot, Avinu Malkeinu and read the Torah. Sephardim add Aneinu to the shaharit amidah. At Minha we read the Torah and Asheknazim add a Haftarah. All insert aneinu in the amidah and Ashkenazim recite Sim Shalom instead of Shalom Rav. Avinu Malkeinu is also said at Mincha.
Some Sepharadim wear their tefillin at minha.
 B. Taanit 12a and S”A OC 564
 I happen to not recommend this popular ritual for physiological reasons -- our bodies “know” how to fast and by having breakfast, you are kick starting your metabolism to expect more food. But it is perfectly acceptable on halakhic grounds.