Today is the public fast day of the Seventeenth of Tammuz.
The Fast of the Seventeenth of Tammuz
The prophet Zechariah (8, 19) states: “So says Hashem, G-d of Hosts: The fourth, fifth, seventh, and tenth fast days shall be for the house of Yehuda for gladness, joy, and good times; [only] love of truth and peace.” Our Sages (Rosh Hashanah 18b) explain that the “fourth fast day” refers to the Seventeenth of Tammuz, for Tammuz is the fourth month when counting from Nissan (Nissan is the first of the months of the year according to our holy Torah). The “fifth fast day” refers to the fast of the Ninth of Av, for Av is the fifth month when counting from Nissan. The “seventh fast day” refers to the Fast of Gedalia which falls out on the third of Tishrei, which is the seventh month from Nissan. The “tenth fast day” refers to the fast of the Tenth of Tevet, which is the tenth month from Nissan.
The Essence of the Fast
The Rambam writes that the entire Jewish nation must fast on these days because of the tragedies that befell them on these days. This will serve to awaken their hearts and open the pathways to repentance. This will also serve as a reminder of our evil deeds and the deeds of our ancestors that resembled our current deeds which eventually caused these tragedies to befall them and us. Upon remembering these things, we shall mend our ways, as the verse states, “And they shall confess their sins and the sins of their fathers.”
What Occurred on the Seventeenth of Tammuz?
The following five terrible events occurred on the Seventeenth of Tammuz: The two tablets bearing the Ten Commandments were broken, the daily Tamid offering brought in the Bet Hamikdash ceased, our enemies breached the walls of Jerusalem in the Second Temple era, the wicked Apostemos burnt the Torah, and an idol was erected in the sanctuary of the Bet Hamikdash.
Those Obligated to Observe This Fast
Everyone is obligated to fast on the Seventeenth of Tammuz. Nevertheless, pregnant and nursing women are exempt from fasting on this day. An elderly person whose health may be affected as a result of the fast (as instructed by a doctor) should not fast. Similarly, a woman who is within two years of giving birth and feels especially weak as a result of the fast need not fast. Any person whose health does not allow him to fast should consult a competent halachic authority regarding how to proceed. If the fast poses a possible danger to one’s life, one should certainly not fast. One should consult with a prominent halachic authority so that the latter can guide the individual how to act with regards to Tisha Be’av, which is a more stringent fast day than others.
Children, i.e. boys under the age of thirteen and girls under the age of twelve, should not fast at all on this day, even for several hours. Only young men and women of Bar/Bat Mitzvah age should fast on this day. The same applies to the public fast days of the Fast of Gedalya, the Tenth of Tevet, and the Fast of Esther. (Chazon Ovadia)