This Halacha is an excerpt from our Sefer
- The date:
The 17th of Tammuz is an established fast day due to the tragedies that occurred on this day. [It is also the beginning of the three-week period of mourning. This fast is explicitly mentioned in scripture [Zecharia 8] as the “Fourth fast”. The fourth fast refers to the fast of the 17th of Tammuz which is in the fourth month.]
17th of Tammuz falls on Shabbos: Whenever one of the four fasts fall on Shabbos, the fast takes place after Shabbos. [Thus, if the 17th of Tammuz falls on Shabbos, the fast takes place on Sunday, the 18th of Tammuz. It is permitted to have marital relations on this Shabbos of the 17th of Tammuz according to all opinions.]
Announcing the fast the Shabbos before: It is not the Ashkenazi custom to announce the fast on the Shabbos before the fast. [Thus, we do not announce the coming fast of the 17th of Tammuz on the Shabbos before the fast.]
The five tragedies that occurred on the 17th of Tammuz:
- Moshe broke the first Luchos upon descending from the mountain and seeing the golden calf.
- The Karban Tamid sacrifice ceased to be offered onto the altar in the period of the first Temple.
- The walls of Yerushalayim were breached during the times of the second Temple.
- Apotomus, the Rasha, burned a Torah scroll.
- Apotomus, the Rasha, set up an idol in the Temple.
The purpose of a fast day:
The purpose of a fast day is to arouse the hearts in true repentance after contemplating the suffering we experienced due to our evil ways. Thus, each person is to do an accounting of his soul during this time.
One must be especially careful to avoid anger on a fast day.
Speaking less and avoiding laughter:
One is to diminish conversation on a fast day, and is certainly to avoid laughter.
Lamenting the tragedies:
One is to lament the tragedies that occurred on that day, for which he is fasting, and not let the fast become like a routine day with simple avoidance of eating.
When the 17th of Tammuz coincides with Shabbos, may one say Shehechiyanu that Shabbos?
Some Poskim rule it is permitted to say Shehechiyanu on that Shabbos even according to the stringent opinion who holds the mourning customs begin that day. Other Poskim argue it is forbidden to do so according to the stringent opinion which holds the mourning customs begin that day. On Friday night, some Poskim rule one may say Shehechiyanu according to all opinions.
- When does the fast begin?
Alos Hashachar: The fast begins by Alos Hashachar of the day of the 17th of Tammuz. There is general dispute amongst the Poskim as to the definition of Alos/daybreak according to Halacha. Some Poskim, and calenders, rule Alos Hashachar begins 72 minutes prior to sunrise. Other Poskim, and calendars, rule Alos Hashachar begins 90 minutes prior to sunrise. Other Poskim, and calendars, rule Alos Hashachar begins two fluctuating hours prior to sunrise, and so is understood by many to be the opinion of Admur. This means that the fast begins when the sun is 26 degrees below the horizon, and does not refer to 120 Zmaniyos minutes. [Practically, those who follow the rulings of Admur, are to be stringent like all opinions, and so is the widespread Chabad custom. Thus, regarding a fast day, one is to be stringent to consider Alos Hashachar to begin approximately two fluctuating hours prior to sunrise. Accordingly, even if one was awake the entire night, or went to sleep on condition to wake up before Alos to eat/drink, he must stop eating and drinking two fluctuating hours before sunrise. Being that different calendars follow different opinions regarding the definition of Alos, it is imperative that by a fast day, one look at a calendar which shows the time of Alos in accordance to the ruling of Admur, which is 2 fluctuating hours before Alos. [The correct time according to Admur can be found in Luach Kolel Chabad, Hiskashrus, Chabad Dvar Malchus, Luach of Rav Sangwai and certain Chabad websites. The time of Alos for a fast day found on Chabad.org is not accurate according to the above understanding of Admur.]
One who woke up before Alos: If one slept a set sleep [even not on one’s bed, such as on one’s couch] and then woke up prior to Alos, he may not eat [anything] unless he stipulated prior to going to sleep that he plans to eat after awaking before Alos. He may however have a drink, even if he did not stipulate before going to sleep that he plans to drink upon awakening before Alos. Nevertheless, if he is not accustomed to drink in middle of the night after awakening, it is initially proper to stipulate before going to sleep that he plans to drink upon awakening before Alos. If one did not make this stipulation, he may nevertheless drink upon awakening before Alos, even if he is not accustomed to drink in middle of the night after awakening. If one did not sleep a set sleep but rather slightly dozed off, it is considered as if he has not slept at all in this regard and he may thus continue eating until Alos. [Nevertheless, some Poskim rule it is a grave prohibition according to Kabala to eat, prior to dawn, after awakening, throughout the entire year. This prohibition applies starting from midnight and onwards, after awakening from a standard sleep of 60 breaths. Practically, the custom of Sephardic Jewry is to be stringent. However, Ashkenazi Jewry is lenient and so is the Chabad custom. If one did not sleep that night for at least 60 breaths, then according to all, he may eat up until dawn. Likewise, some Poskim rule that if one plans to return to sleep for a second time before Alos, then this prohibition does not apply. Likewise, if one is weak or sick he may eat prior to Alos even according to the Zohar.]
Eating within 30 minutes prior to Alos: It is forbidden throughout the year to begin a meal starting from 30 minutes prior to Alos [however, snacking is allowed]. [One may eat up until 55 grams of bread, and Mezonos, and an unlimited amount of fruit and drink.]
May one eat a lot of food prior to a fast in order so he does not feel hungry?
The Poskim rule that one may not eat more than usual prior to a fast, as this defeats the entire purpose of feeling oppression on that day. Nevertheless, one who is weak natured, and needs to eat a lot more food than usual in order to have strength, may do so.
May one take a fast-easy pill [Kali Zom] in order to alleviate the fast?
This follows the same ruling as above.
May one eat meat and drink wine on the night of a fast?
Some are accustomed not to do so.
If one went to sleep without stipulation and then ate prior to Alos, is it considered as if he broke his fast?
- When does the fast end?
All fasts conclude after nightfall. This is defined as the sighting of three medium stars, or when the moon shines very brightly on the earth. It however does not suffice to see three large stars. [Practically, in Eretz Yisrael, some say that this is approximately 17 minutes after sunset by regular fasts and 24-27 minutes after sunset by Tisha B’av. Others say it is 27 minutes after sunset by all fasts of the winter, and 34-35 minutes after sunset by all fasts of the summer. According to the rulings of Rav Avraham Chaim Naah, nightfall in Eretz Yisrael is between 15-20 minutes after sunset in the winter and 20-26 minutes after sunset in the summer. In New York, some write one is to wait until 50 minutes after sunset, or at the very least 41 minutes after sunset. The Rebbe stated that in New York nightfall throughout the year is 36 minutes after sunset, both during the summer and winter. In all cases, one may begin Maariv before the above time, in order to conclude Maariv and be able to eat when the above time arrives. In such a case, one is to make sure to read Kerias Shema again after nightfall.]
If one is flying on a fast day and is extending or hastening the sunset, when is he to break his fast?
He is to break his fast as soon as Tzeis Hakochavim arrives in the area that he is currently in. Thus, if he flew from the U.S. to Israel and is hence hastening the coming of Tzeis Hakochavim, he may to break his fast as soon as Tzeis Hakochavim arrives on his plane. If, however, he flew from Israel to the U.S. and is hence delaying the time of Tzeis Hakochavim, then he is to fast until Tzeis Hakochavim arrives while he is on the plane. Some Poskim however rule that when flying to the west, one may be lenient to break his fast in accordance to the area that he left from, upon Tzeis Hakochavim arriving there.
When does the fast end in countries with long days, such as near the North pole?
If one crossed the international dateline on a fast day from West to East, is he to fast again the next day?
 Michaber 549:1
The 9th of Tammuz: Although the verse states that the walls of Jerusalem [in times of the 1st Temple] were breached on the 9th of Tammuz, nevertheless we do not fast on the 9th of Tammuz, but rather only on the 17th of Tammuz. The reason for this is because the breaching of the walls on the 9th of Tammuz were by the times of the 1st Temple, while the breaching of the walls of the 17th of Tammuz were of the 2nd Temple, and the destruction of the 2nd Temple is of greater severity to us. [Michaber 549:2] It was thus instituted to fast on the 17th of Tammuz as opposed to the 9th of Tammuz, as to fast both days is too much of a trouble for the public, and since the 17th is more severe, we therefore fast only on the 17th. [M”A 549:2; Ramban] Nevertheless, a meticulous person should also fast on the 9th. [M”A 549:2] The Jerusalem Talmud however writes that the breach of both walls occurred on the 17th of Tammuz, and the verse which had written that it occurred on the 9th had made a mistaken calculation. Due to the suffering, they made a mistaken calculation. [M”A 549:2] Accordingly, there is no reason for even a meticulous person to fast on the 9th. [Machatzis Hashekel ibid]
 See Levushei Serud 549; Kaf Hachaim 549:1
 Michaber 550:3; Rambam Taanis 5; Mishneh Megillah 5 as explained in Rashi
 Ashel Avraham Butchach 550; Piskeiy Teshuvos 550:9
 Rama 550:4
Other opinions: Some Poskim rule that the Shabbos prior to a fast the Chazzan should announce the coming fast, with exception to the fasts of Yom Kippur, Tisha B’av and the fast of Esther. [Michaber 550:4; Abudarham; Kaf Hachaim 550:24] The Rama writes that the Ashkenazi custom is to not announce any fast.
 Mishneh Taanis 26b; Rambam Taanis 5:2; M”B 549:2; Kaf Hachaim 549:4; Kitzur SH”A 121:4
 Rambam Taanis 5:4; M”A 549:1; Kaf Hachaim 449:2
 Shlah p. 200b; Elya Raba 568:18; Kaf Hachaim 550:11; M”B 568:50
 Yesod Veshoresh Havoda 11
 Seder Hayom Inyanei 17 BeTammuz
 M”A 551:42, brought in Beir Heiytiv 551:38; Elya Raba 551:42; Ramaz brought in Birkei Yosef 551:11
 Mor Uketzia 551; Birkeiy Yosef ibid; Chaim Sheal 1:24; Kaf Hachaim 551:206
 Sdei Chemed Bein Hametzarim 1:1; Nitei Gavriel p. 118
 See Michaber 550:2 “One is not required to start fasting Mibiod Yom”
 Rashal Pesachim 2a; Minchas Kohen 2:6; M”A 89:2; Levush 261 and 459; Admur in 89:1, 184:3, and 261:5; Derech Hachaim; M”B 89 in Biur Halacha “Veim”; 58 Biur Halacha “Kemo”; and chapters: 92; 163; 235; 261; 459; This opinion is based on the calculation that there are 18 minutes per Mil [as rules Terumos Hadeshen 123; Michaber 459:2; Yoreh Deah 69:6; Rama 261:1; Admur in 89:1, 184:3, and 261:5] and there are 4 Mil between Alos and Neitz [as rules Rebbe Yehuda in Pesachim 94a] Accordingly there are 72 minutes before Alos, as 18 x 4=72.
 Gr”a 459; Chok Yaakov 459:10; Chasam Sofer in glosses 89] This opinion is based on the calculation that there are 22.5 minutes per Mil [as rules Mahril in Hilchos Pesach] and there are 4 Mil between Alos and Neitz [as rules Rebbe Yehuda in Pesachim 94a] Accordingly there are 90 minutes before Alos, as 22.5 x 4=72.
 Ruling of Admur in accordance to Harav Hagaon Avraham Chaim Naah printed in Shiureiy Mikveh 37; Yagdil Torah Tzemach Tzedek 23 p. 23 [see there for a full organized summary on the subject]; See Shiureiy Tziyon 37; Yagdil Torah Tzemach Tzedek 23 p. 23; Siddur Raskin p. 625 and Miluim 27 [summary of opinions according to Admur]; Rav Sangwai in Habracha 5:162 [defends and proofs the opinion of Gra”ch Naah in Admur and that so learned the Rebbe to be the opinion of Admur]; Piskeiy Teshuvos 89:2
Rulings of Admur: Admur wrote different calculations regarding Alos Hashachar throughout the Shulchan Aruch, Siddur and Tanya. This created confusion as to Admur’s opinion as to the time of Alos Hashachar. From 89:1, 184:3, and 261:5 it is calculated that Alos Hashachar is 72 minutes before sunrise, or possibly 96 minutes. In 249:3, 459:10 and the Siddur [Seder Hachnasas Shabbos] it can be calculated that Alos Hashachar is 96 minutes or 120 minutes before sunrise. From the time of Alos mentioned in the Siddur regarding Sefiras Haomer it is possible to calculate it as 72 or 120 minutes. In Igeres Hateshuva 3 Admur extends the time of starting a fast to three hours before sunrise. The following are the opinions of Chabad Rabbanim in this matter:
Opinion of Admur according to the Gra”ch Naah-Two fluctuating hours: Rav Avraham Chaim Naah ruled that according to Admur, Alos Hashachar begins two fluctuating hours prior to sunrise. [Shiureiy Tziyon 37; Yagdil Torah Tzemach Tzedek 23 p. 23] The calculation is as follows: There are 5 Mil between Alos and Neitz [as rules Ula in Pesachim 93b]. Each Mil is 24 minutes [as rules Rambam in Pirush Hamishnayos Pesachim 3:2]. Thus 24 minutes per Mil x 5 Mil between Alos and Neitz equals 120 minutes. [This follows the ruling of Admur in 249:3; 459:10 and Siddur and so rules regarding 24 minutes per Mil: Peri Chadash Y.D. 69:26; Kitzur SHU”A 36:11. However, in 89:1 and 261:5 Admur rules that there is only 4 Mil between Alos and sunrise, hence there is only 96 minutes between Alos and sunrise. As well, although in 459:10 Admur rules that the day begins from sunrise and ends by sunset, in 89:1 he rules that it begins from Alos until nightfall. Nevertheless, the final ruling of Admur follows the ruling of the Siddur in which Admur rules like in 459:10.]
Other opinions amongst Chabad Rabbanim: See article of Rav Raskin in Siddur Miluim 27, and Rav Sangwai in Habracha, for a summary of opinions of Chabad Rabbanim regarding the time of Alos Hashachar according to Admur. The opinions vary between 120 minutes, 72 minutes, 90 minutes and 96 minutes.
Opinion of three hours before sunrise: In Tanya, Igeres Hateshuva 3, Admur writes that one may eat up to three hours before sunrise, of a penitential fast. This implies that by a fast day one is to begin fasting even before Alos, when 1:3rd of the night has entered. [See Igros Kodesh 18:557] It requires further analysis however if this applies to all fasts, or just a penitential fast. [Sefer Haminhagim p. 45] However, from Admur in Siddur by Sefiras Haomer, it is implied that one may eat on a fast day up until Alos. [Hiskashrus 424:18 footnote 113] Likewise, Rav Groner states that he heard clearly from the Rebbe that the three hours is only applicable by a penitential fast. [Hiskashrus] However in Sichos Kodesh 2:494 the Rebbe mentioned a scrupulousness to begin the fast some time before Alos Hashachar. Vetzaruch Iyun.
 Definition of fluctuating hours: This means that the hours fluctuate in the winter and summer. Some Poskim rule this means it fluctuates in terms of Zmaniyos, meaning that it depends on the amount of hours in the day. Thus in the summer, the hours will be longer [between 120-150 minutes for two hours] while in the winter they will be shorter [between 90-120 minutes for two hours]. [So rules Minchas Cohen 2:6; Rama 233; Peri Chadash 58] However the Alter Rebbe and Gr”a both rule that it follows not the amount of hours in the day but rather the degree of distance of the sun from the horizon. [Admur in Seder Hachnasas Shabbos; Gr”a in 261; See Shut Mahrshag 2:34 quoted in Piskeiy Teshuvos 89:2 footnote 59 that this is the way we rule.] Thus, those who hold that Alos is 72 minutes it ends up being in Tishrei and Nissan 16.1 degrees from the horizon and the amount of time it takes the sun to travel to the horizon fluctuates between winter and summer. [See Piskeiy Teshuvos 89:2] According to Admur however who holds of 120 minutes, this would be when the sun is 26 degrees below the horizon.
Other opinions: Some Poskim rule we always measure the hours as set hours and hence there will always be only 120:90:72 minutes between Alos and sunrise at all times. [Admur 89:1; Birkeiy Yosef 261:1; Peri Megadim 261 A”A 9; Derech Hachaim; Siddur Yaavetz; Machatzis Hashekel 235:3]
 See the previous footnote
 Shiureiy Tziyon ibid; It is important to note that there are Chabad Rabbanim who take a different approach in their understanding of the opinion of Admur, and each person is to follow his Rav. [See opinions of other Chabad Rabbanim in previous footnotes.] Those, who do not necessarily follow the rulings of Admur, should speak to his Rav for a final ruling regarding this matter, and which time, and calendar he should follow.
 M”B 564:3
 P”M 564 A”A 3
 Michaber 564:1
 Rama 564:1 being that it is common to drink upon awakening in middle of the night and hence it is considered as if one stipulated even if one did not explicitly do so.
Other Opinions: The Michaber ibid rules one must stipulate even in order to drink upon awakening.
 So learns M”B 564:6 in M”A 565:3 that even initially it is not required to stipulate if he is accustomed to drink
 M”A 564:3; Levush 564; Bach 564; M”B 564:6 in name of Elya Raba. However, if one did not stipulate he may nevertheless drink. [M”B ibid and in Shaareiy Tziyon 564:7]
 M”B 564:6 in name of Elya Raba; Shaar HaTziyon 564:7; Kaf Hachaim 564:10
 Michaber 564:1; M”B 564:2-3
 M”A 89:14 in name of Tov Haaretz, Rav Chaim Vital and Zohar 2:215; Beir Heiytiv 581:12 in name of Zohar and Kisvei Arizal; Chida in Machazik Bracha 581:5; Birkeiy Yosef 89:1 [Shiyurei Bracha] in name of Mekubbalim; Yosef Ometz 17:2; Mishnas Chassidim Chatzos 7; Or Hachama Zohar ibid; Nitzutzei Oros Zohar ibid; Kaf Hachaim 581:69; 89:28-31]
The reason: As one who eats food past midnight after awakening adds vitality to the Kelipos. [Rebbe ibid] It is however not prohibited due to the prohibition of eating prior to prayer, as this prohibition only begins from Alos. [89:5; Rebbe ibid]
Other Poskim: Some rule that even according to Kabala there is no need to refrain from eating prior to Alos. [Heishiv Moshe 6 based on Siddur Arizal of Rav Shabsi of Rashkov that Rav Chaim Vital ate before Alos; Maharil and Rama ibid]
Opinion of Shulchan Aruch Harav: In Igeres Hateshuvah chapter 3 Admur writes that one may eat prior to three hours before sunrise on a fast day. The Rebbe in Igros Hakodesh 3:75 writes that this ruling only was said regarding when the prohibition of eating prior to a fast begins and is not discussing the prohibition of the Zohar, which in certain cases is allowed. Nevertheless a proof can be brought from Admur 89:5, which omits this law of the M”A ibid brought from the Zohar, that Admur rules it is permitted.
 So is evident from M”A ibid; Beir Heiytiv ibid; and other Poskim; Igros Hakodesh 3:75
 Kaf Hachaim ibid
 Shvus Yaakov 3:41 defends the ruling of Rama; Some Poskim write that the current Ashkenazi custom is to only be lenient to allow to drink coffee or tea prior to Alos, although regarding eating food they are careful. [Shaareiy Teshuvah 581:12; M”B 581:21]
 See Igros Hakodesh 3:75 [brought in Shulchan Menachem 1:44] that so is the ruling of Admur. It is our custom to allow one to eat after Alos before Davening in order to have strength to Daven. Certainly then, one may be lenient to eat before Alos in order to have strength to Daven.
 P”M 89 A”A 14; Igros Hakodesh 3:75
 Ashel Avraham Butchach [Tinyana] 89; See there that he connects the prohibition of the Zohar to the prohibition of eating before Davening.
 Nitzutzei Oros Zohar ibid; A”A 89 in name of Shev Yaakov [brought in Igros Hakodesh ibid]
 Admur 89:5; Rama 581:2; M”B 89:27 in name of Derech Hachaim and Rav Akiva Eiger
 Piskeiy Teshuvos 564:1
 Kaf Hachaim 550:11; See Piskeiy Teshuvos 564:1
 Kitzur Shlah; Nehar Shalom 550:2; Elya Raba 563:1; Bigdei Yesha 564
 Seder Hayom Inyanei Bein Hametzarim; See Piskeiy Teshuvos 550:8; 564:1
 See Shevet Hakehasi 1:180; Piskeiy Teshuvos 564:2
 Michaber 562:1; See Piskeiy Teshuvos 562:1
 Michaber 562:1; Rosh; Rav Chisda in Taanis 12 “Whoever did not fast until sunset is not considered to have fasted.” Igros Moshe 4:10 rules that in New York one is to wait until 50 minutes after sunset, and at the very least wait 41 minutes.
Other opinions: Some Poskim rule it one is only required to fast until the start of Bein Hashmashos. [Sefas Emes Taanis 12; Aruch Hashulchan 562:9 based on Rambam, Rashi, Ran] This however is in reference to Zman Rabbienu Tam, and not to the Zman of the Geonim. [Biur Halacha Tinyana 562; Piskeiy Teshuvos 562:1]
 Rama ibid; Hagahos Ashri; Hagahos Maimanis
 M”A 562:1 as corrected by Machatzis Hashekel ibid; Levushei Serud ibid; P”M 562 A”A 2
 Luach Eretz Yisrael of Harav Tukichinsky
 Sefer Birur Halacha, brought in Piskeiy Teshuvos 562:1
 See Ketzos Hashulchan 93 footnote 2; Shiureiy Tziyon of Grach Naah p. 76
 Igros Moshe 4:62; See Rebbe in Igros Kodesh 17:124 [printed in Shaareiy Halacha Uminhag 155 and Shulchan Menachem 2:123]
 Heard from Rabbi Leibal Groner; See Hiskashrus 370:19; Rav Raskin in Siddur p. 230
 Mateh Efraim 602:29; Igros Moshe ibid; Piskeiy Teshuvos 562:1 footnote 2; Rabbi Groner that so was directive of Rebbe to ask Rav Shmuel Levitan one year on a fast day to Daven before the time of nightfall and announce to everyone to say Shema again after nightfall; See Hiskashrus 1198
 Igros Moshe 3:96; Betzeil Hachochmah 1:31; Chavatzeles Hasharon 1:43; Yaskil Avdi 8:31; Piskeiy Teshuvos 562:2; See Nitei Gavriel Bein Hametzarim 4:5
The reason: As there is no precedence in Poskim to allow one to break one’s fast based on the area that he started his fast, and hence since the law states that the fast does not end until Tzeis Hakochavim, one may break the fast when it reaches Tzeis Hakochavim in his area, whetehr this is earlier, or later, than his original location. [Igros Moshe ibid]
 Shevet Halevi 8:261; See Nitei Gavriel ibid
 The reason: A the Sages never decreed for one to fast more than the normal hours, and hence one may break his fast as soon as the fast is over in his original location. [ibid]
 See Piskeiy Teshuvos 562:2
 Nachal Eshkol Tisha B’av
 Daas Torah 549; Shevet Halevi 7:76
 Betzeil Hachochma 1:31