When Asarah B'Tevet falls on a Friday, tefillot are conducted exactly as they would be on any other day of the week, except that at Minhah, Avinu Malkeinu and Tahanun are omitted.
With respect to the conclusion of the fast, a dilemma emerges: Mishnah Megillah 1:3 clarifies that when 9 Av falls on Shabbat, it is pushed off to Sunday; this aversion to fasting on Shabbat would seem to extend to all other public fasts as well, with the exception of Yom Kippur. [Note an unusual claim in R. David Abudraham that if 10 Tevet fell on Shabbat, it would also be observed on Shabbat, but Rashi on Megillah 5a disagrees and Beit Yosef OH 550 rejects this view.] This flags a general tension between fasting and Shabbat that raises the question of how to deal with a Friday fast. Such a fast, if completed until nightfall, will extend into Shabbat. Should the fast be completed until nightfall, in keeping with the integrity of the day? Or does the sanctity of Shabbat allow for or even require truncating the fast in some way? And if so, is there any integrity to a fast day that is truncated before the end of the day?
Two core texts address this matter:
- In Mishnah Ta'anit 2:10, R. Meir reports in the name of Rabban Gamliel that when Tish'a B'Av fell on a Friday-[this is no longer possible given current calendrical rules]-the fast would not be completed.
- Tosefta Ta'aniyot 2:7 also discusses the case of Tish'a B'Av falling on Friday. R. Yehudah says that a person eats and drinks a small amount before Shabbat so as not to enter into Shabbat in a state of fasting. [In the parallel in the Bavli, R. Yehudah says that he based his view on once seeing R. Akiva force himself to eat something before Shabbat when 9 Av fell on a Friday so as to show people that the law required eating prior to Shabbat.] R. Yose says the fast is completed even though it runs into Shabbat (which seems to mean that one fasts until nightfall). From the context in the Tosefta, this seems to be a debate spanning the full spectrum of possibility: R. Yehudah requires one to eat before Shabbat begins, but R. Yose also requires one to fast into Shabbat and not to cut the fast short.
In Yerushalmi Ta'anit 2:14, Rav is quoted as siding with R. Yose's position in the Tosefta, and mandating the completion of the fast of Tish'a B'Av into the time of Shabbat. This view is also reflected in Bavli Eruvin 40b-41b, where both Rav and Ulla rule this way as well. [Rav is cited as explicitly rejecting Rabban Gamliel's position. The Gemara states that R. Yose's opinion over time gained dominance over that of Rabban Gamliel cited in the Mishnah.] The sugya there ends with a public ruling in the name of R. Huna that one completes the fast, which seems also to refer to siding with R. Yose over R. Yehudah with respect to Tish'a B'Av falling on a Friday.
On Eruvin 40b, Rabbah reports a question: does one who takes on an optional fast on a Friday complete the fast into Shabbat or do they cut it short in anticipation of Shabbat? [This question is answered clearly in the Yerushalmi: the fast is completed into Shabbat. But note the tradition recorded in Megillat Ta'anit that frowns on electively choosing to fast on Friday.] Rava appeals to the R. Yose's position in the Tosefta above to resolve this question, assuming that the rule for an individual fast ought to be the same as for a public fast like 9 Av. From a historical perspective, it seems fairly clear that by Rabbah and Rava's time, the question with regard to 9 Av had been definitively resolved. Therefore, Rabbah's question seems to be entertaining the possibility that an elective fast might be treated more leniently, and the Gemara concludes that it cannot; it too must last until nightfall into Shabbat. Alternatively, it is possible that the question here is more radical: Do we follow R. Yehudah on individual fast days and actually forbid fasting into Shabbat, or do we permit individuals who want to to fast until nightfall on Friday night? Under this reading, the sugya's conclusion would merely be that it is permissible to fast until nightfall, but by no means obligatory.
A number of positions emerge from this material in the rishonim:
- Tosafot on Eruvin 41b explain R. Yose according to the latter reading above: it is permitted to fast into Friday night, but even he agrees that it is not obligatory. Moreover, they extend this reading into the core holding on 9 Av. Therefore, there is never an obligation to complete a fast on Friday and it may be broken before Shabbat. Ri (cited in Mordechai and Darkhe Moshe OH 249) is reported to have publicly broken his fast before the onset of Shabbat one year when 10 Tevet fell on a Friday. This view does not specify how early one can break the fast; it would seem to be an allowance to eat enough sufficiently in advance of Shabbat (i.e. not just 30 seconds before), so that one does not enter Shabbat feeling ravenous.
- Maharam of Rothenberg adopts a softer version of the above: one who has accepted Shabbat early, as one who prays Arvit before it is dark, may eat before nightfall when it is a fast day on Friday. One could thus begin Shabbat as early as P'lag Haminhah (just under 1 hour before sunset in the winter in New York City, 3:31 PM this year) and then eat right after Arvit. [This reflects Maharil's tradition regarding Maharam; the version of Maharam reported in Tashbetz Katan may be slightly stricter, possibly advocating waiting until at least sunset. See Bah OH 249.]
- Ra'avad (cited in Rashba and many others) ruled that the requirement to complete the fast was only to forbid eating before Shabbat (as Ri did), but once the sun has set, one may break the fast immediately and not wait until nightfall, since it is Shabbat and one may not fast on Shabbat. [See also Tosafot Avodah Zarah 34a for a possible antecedent to this view.] He does not explicitly address the case of one who accepts Shabbat early, but it seems he is stricter than the second view above.
- Ra'aviah holds (along with others) that one must complete all fasts, private and public, until nightfall, even if they fall out on a Friday.
Rosh, though he accepts Maharam's position in principle, rules that one who does not mentally note that one will end the fast early has an obligation to complete the fast into Shabbat and until nightfall. This is essentially an adoption of Maharam's view as an option to be exercised, with Ra'aviah's position serving as the default.
Two positions emerge that attempt to distinguish between private and public fasts: Maharil Responsa #157 reports his own practice as following Maharam for elective fasts and following Ra'aviah for public fasts. But he is explicit that he thinks either option is valid to choose for either. R. Yeroham is stricter: He thinks that one may not exercise Maharam as an option for a public fast day and must complete it until nightfall.
Rema endorses a purer version of Maharam that prefers but does not require advance acceptance and recommends eating before nightfall, but then reports Maharil's personal practice as the common standard for public fasts (essentially following R. Yeroham). Shulhan Arukh rules like Rosh, requiring explicit acceptance of a truncated fast in order to eat after Arvit and before nightfall. Kaf Hahayim is clear that one may use this mechanism for a public fast as well, though R. Ovadiah Yosef reads R. Yeroham into the Shulhan Arukh here and claims that, according to the Shulhan Arukh, public fasts must always be completed until nightfall (even though he rules that elective fasts may be ended immediately after Arvit).
In our own time, it would seem that the answer to this question will be determined by how one regards the status of 10 Tevet in our day. Obviously, those who view the fast today as elective (see my thoughts on this here; key sources are here) and choose not to fast (or those who view it as forbidden to fast) will not do so. But among those who do fast, there are two basic possibilities:
- Those who consider 10 Tevet to be fully obligatory should fast until nightfall, following Maharil as reflected in Rema, though there is room for those with no tradition in this regard to follow Rosh as reflected in Kaf Hahayim's interpretation of the Shulhan Arukh. The latter view allows one to state on Thursday afternoon that one only intends to fast until the end of Arvit on Friday night and then one may eat even before nightfall, as early as Plag Haminhah. But if one forgot to state this explicitly on Thursday, one should complete the fast until nightfall.
- Those who consider 10 Tevet as elective, but choose to fast, should state on Thursday afternoon that they only intend to fast until the point on Friday at which they intend to eat-whether that be the end of Arvit on Friday night or perhaps even right after Minhah on Friday afternoon. [See below for more on a half-day fast.] According to Rema, it is desirable to eat before nightfall when taking on an optional fast on a Friday. Therefore, even if one forgot to commit to this on Thursday, one may/should still end the fast after praying Arvit, even if it is as early as Plag Haminhah.
Can you fast half a day in general?
One of the core questions with regard to an optional fast is whether one can decide to take it on "halfway". For instance, if one wants to mark the day as significant through fasting, can one begin fasting in the morning, continue through midday, pray Minhah with the fast-day addition of Aneinu and then eat in the early afternoon?
Indeed, we have a few examples of fasts that were truncated earlier in the day. Mishnah Ta'anit 2:6 speaks about the behavior of the priests on duty in the Temple when fasts were being declared for lack of rain. We are told that during the initial two sets of three fasts, at least some of the priests on duty only fasted a partial day. Tosefta Ta'anit 3:6 features R. Elazar bR. Tzadok reporting that his family was descended from those who performed an important Temple service on the 10th of Av, making this a joyous day for them. When 9 Av fell on Shabbat, such that the fast was pushed to Sunday, his family would only fast a partial day. These both seem to be cases of fasts that were begun in the morning (or the night before) and then ended early midway through the day.
The Talmudim then take up an even more targeted category of תענית שעות-a fast that only lasts a set number of hours.
In Yerushalmi Nedarim 8:1, we are told that R. Yohanan used to declare himself to be in a fast until he finished a section of learning he was engaged in. When he would complete his learning, he would then eat. We are told that R. Yonah, when he heard of his brother's death, fasted the rest of the day even though he had already ate and drank that morning. These stories are both cited as evidence of the validity of תענית שעות-a fast that lasts a targeted number of hours. [Rav is cited as support for this view as well.] This notion is not contested there and there seems to be no requirement that the day begin or end with fasting. [Perhaps a stricter reading of R. Yohanan would imagine him as not yet having eaten when pledging to fast until the end of his learning.] The Yerushalmi seems to proceed to indicate that this is all contingent on planning for the fast to be targeted in advance. One who makes a general commitment to fast and then eats out of weakness will need to fast all over again on another day. On Bavli Ta'anit 11b, there is indeed a legal pronouncement that מתענין לשעות-such targeted fasts for only a portion of the day are indeed valid. Abaye there also seems to clarify that one who fasts a targeted fast would add the special additions for a fast day into the Amidah.
On Bavli Ta'anit 12a, Shmuel makes a general point about the need for any optional fast to be explicitly accepted at Minhah the day prior. It is not clear if he believes this to apply to a תענית שעות as well.
On Bavli Ta'anit 12a, R. Hisda says that any fast that does not run through the end of the day (sunset) is not a valid fast. The Talmud then cites the cases of the priests and R. Elazar bR. Tzadok's family; in both cases, people did end their fast before the end of the day. The Talmud deflects these practices as being devoid of the status of a real fast; essentially, these people electively decided to adopt an ascetic practice, but it has no liturgical/ritual meaning to it. The Talmud also cites a version of the tradition about R. Yohanan in the Yerushalmi, where he commits to a fast until he arrives home from the Patriarch's house, which he was visiting or was summoned to. That case is dismissed as R. Yohanan making that public pronouncement so he could extricate himself from the Patriarch's presence.
Finally, there is a statement by R. Hisda that appears in two different versions and is read differently by different commentators. Rambam understands his ruling to invalidate a fast that is ended early (before the end of the day), but consistent with beginning a fast midway through the day (like R. Yonah's practice in the Yerushalmi). In other words, a private fast must always end at sunset/nightfall, but it can begin whenever one wants, as long as it is planned out that way in advance. This reads R. Hisda's two statements as making the same legal point, in different words and in different textual contexts. Rashi and Ra'avad read R. Hisda as forbidding beginning a fast late, just as his prior statement forbade ending it early. In other words, for Rashi and Ra'avad, the collective effect of R. Hisda is to eliminate the ritual/liturgical possibility of a half-day fast. The only meaning of תענית שעות is that a person who fasted an entire day but only did so with intention starting part way through can get credit for a full-day of fasting and have it be ritually/liturgically meaningful. Both Rambam and Ra'avad follow the Bavli's seeming conclusion that ending a fast early does not have ritual/liturgical meaning.
Shulhan Arukh OH 562:1 affirms that a partial day fast is not ritually/liturgically meaningful.
Terumat Hadeshen #157, however, reports that the practice in his community is for grooms to fast a partial day when a wedding is held on Friday afternoon, and argues that this practice is consistent with the permission for תענית שעות, without fully making his case. Rema settles on a kind of compromise position: 1) A part-day fast by a community cannot trigger changes in communal liturgy, such as the added berakhah in the public Amidah. 2) One may commit to fasting part of the day and add Aneinu into the private Amidah, since this is added into שמע קולנו, the blessing that is a fitting receptacle for all private requests. The partial day fast has enough integrity to be referred to as ביום צום תעניתנו. This practice is affirmed by Magen Avraham, Mishnah Berurah and many other later authorities.
In sum, one taking on an optional fast day (which includes the case of one who chooses to fast on public fast days that s/he believes are optional today), can choose to fast until Minhah, insert Aneinu into Minhah and then break the fast. But no changes should be made to the public Amidah in Minhah in that situation, even if the entire community is fasting a partial day.