Fasting on Erev Rosh Hashanah:
Is one to accept the fast the Mincha prior? It is not necessary to accept the fast the Mincha beforehand. [If one accepts the fast the Mincha prior then he is obligated to fast until nightfall. For this reason one should refrain from doing so.]
When does the fast begin? The fast begins from Alos/dawn of Erev Rosh Hashanah.
When does the fast end? One is not to fast the entire day. Many fast until the time of Mincha Gedolah, upon which they daven Mincha and then eat. In such a case one says Aneinu in the private Shemoneh Esrei of Mincha [however not during Chazaras Hashatz]. If however one ate before Mincha, Aneinu is not said. Some Poskim say one may even initially eat prior to Mincha. This especially applies if a Minyan is not currently available, or one is unable to Daven with concentration.
Eating before Alos/dawn: Many are accustomed to eat before dawn of the fast in order to negate the custom of idolaters to fast on the eve of their holidays. One may eat before dawn even if he went to sleep without stipulating to eat upon waking up before dawn. [Nevertheless some Poskim rule it is a grave prohibition according to Kabala to eat, prior to dawn, after awakening, throughout the entire year, and this prohibition likewise applies prior to a fast. This prohibition applies starting from midnight and onwards after awakening from a standard sleep of 60 breaths. Practically the custom of Sefaradi 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 he may eat according to all 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.]
One who is weak or sick: One who is slightly sick should not fast, [rather he should redeem the fast with charity]. [Some write that due to our weak state health one is not to fast at all on Erev Rosh Hashanah and rather is to redeem the fast with charity.]
Seudas Mitzvah: One may participate in a Seudas Mitzvah on Erev Rosh Hashanah. This applies even if one is generally accustomed to fast on Erev Rosh Hashanah. [Nevertheless he is not required to eat if he so chooses unless he is part of the Minyan of ten in which case it is a Mitzvah to eat. Certainly the Baal Bris which is the father, Mohel and Sandek are required to eat and cannot fast. They may eat even prior to the Bris, although the other guests are to fast until the Bris.]
Kerias Hatorah: The congregation does not read the portion of Vayichal from the Torah scroll as this fast is not a public fast.
Fasting for ten days: Those which are meticulous are accustomed to fast for a total of ten days See “Aseres Yimei Teshuvah” Halacha 4 for the full details of this subject!
It is accustomed to fast on Erev Rosh Hashanah until midday. Those which are weak and are unable to fast do not need to do so. Many people today are accustomed to be lenient regarding this fast.
Sparks of Kabala:
Although fasting during Aseres Yimei Teshuvah is an act of piety nevertheless the main Tikkun during these days is actually fulfilled through eating. The fasting is only done due to the requirement to achieve atonement for sin. It is therefore written in Sefarim that one must eat bread every night of Aseres Yimei Teshuvah in order to recite the blessing of Birchas Hamazon.
The Beis Yosef 581 writes in the name of Hagahos Maimanis that in the Pesikta it states it is a Mitzvah to fast on Erev Rosh Hashanah. In the Yerushalmi Taanis 2 it states that Rebbe Yonason would fast every Erev Rosh Hashanah. [Kaf Hachaim 581/70] A support for this fast can be found in the Midrash Tanchuma which states that there is a set of three fasts which gain our forgiveness from Hashem. These three fasts are on Erev Rosh Hashanah; Aseres Yimei Teshuvah and Yom Kippur. On each day Hashem forgives a third of the sins. This is similar to a town that owes taxes to the king and the king approaches the nation for payment. At first the leaders greet the king and he forgives 1/3 of the tax. Then the average citizen greets the king and he forgives another 1/3 of the tax then the entire town greets the king and he forgives the remaining 1/3. Similarly before Rosh Hashanah the leaders fast, by Aseres Yimei Teshuvah the Beinonim fast, and on Yom Kippur everyone fasts. [Tur 581; Levush 581; Kaf Hachaim 581/56] Another reason for fasting is because a person who does Teshuvah one day during the year is considered as if he repented the entire year. Therefore on the last day of the year we fast and wake up early to add in Selichos. [Chayeh Adam 138/5; Kaf Hachaim ibid]
Malkus: Some have the custom to receive Malkus on Erev Rosh Hashanah while others do so on Erev Yom Kippur. It is however best to do so on Erev Rosh Hashanah as Zerizin Makdimim, as well as one should enter into the Holiday clear of sin. [Yifei Laleiv 2/5; Kaf Hachaim 581/58] The Chabad custom is to do so only on Erev Yom Kippur. [Admur 607/11]
 See P”M 581 A”A 9; M”E 581/38; M”B 581/16; Kaf Hachaim 581/57
 Siyum Misechta: Some are accustomed even initially to exempt this fast with a Siyum Misechta. [See Piskeiy Teshuvos 581 footnote 130; Alef Lamagen 581/77]
 Some write that due to our weak state of health one is not to fast at all on Erev Rosh Hashanah and rather is to redeem the fast with charity. [Halichos Olam 581/48 brought in Shevach Hamoadim footnote 15]
 The Chabad custom: The following works which specialize in Chabad customs record this fast day without reservation: Luach Kolel Chabad; Shevach Hamoadim p. 10. The fast is mentioned without mentioning any discrepancy in Chabad custom. However in Otzer Minhagei Chabad 49 after mentioning the accustomed fast he ascertains that it seems the Rebbe did not fast on Erev Rosh Hashanah based on the fact the Rebbe went to the Ohel on Erev Rosh Hashanah and was always particular to drink prior to going. Likewise the Rebbe never went to the Ohel on a fast day. Perhaps however one can suggest that it is for this exact reason that the Rebbe went to the Ohel after midday, as he fasted until midday and then had a drink prior to going. Practically I asked Rabbi Leibel Groner as to whether the Rebbe fasted on Erev R”H until midday and he replied to me: “The Rebbe did not fast on Erev R”H until Chatzos”. In Hiskashrus no mention is made of this fast, and in the footnotes he records the statement mentioned in Otzer ibid. In Halichos Olam 581/48 he writes that due to our weak state of health one is not to fast and is rather to redeem the fasts with charity.
Fasting for those that visit the cemetery: Tzaruch Iyun how those which go to Kivrei Tzaddikim on Erev Rosh Hashanah are to act regarding this fast as one is supposed to drink before going to a Kever in order so it not be Doreish El Hameisim. [See Halacha 7 and Supplement provide in the back of the book] Perhaps in such a case one should wake up before Alos and drink and stay up from then until he visits the cemetery and this is considered as if he drank before going. Vetzaruch Iyun as perhaps one must drink past Alos. On the other hand a simple advice is to visit the cemetery past midday and fast until midday.
 M”A 581/9; Maharil 33
 P”M 581 A”A 9; Machatzis Hashekel 581 “Tinokos” in name of Elya Raba; M”E 581/38; M”B 581/16; Kaf Hachaim 581/57
 M”B 581/16
Other opinions: The Kaf Hachaim 581/62 writes that it is proper to accept the fast the Mincha prior. One who does so is then required to fast until nightfall.
 See Admur 249/12; Piskeiy Teshuvos 581 footnote 127
 M”B 581/21
 Rama 581/2 regarding the ten fasts; M”A 581/10 regarding the fast of Erev Rosh Hashanah
The reason: As one is required to bring in Yom Tov prior to night [sunset] due to the Mitzvah of Tosefes Yom Tov, [and one may not fast for even one moment on Yom Tov]. [M”A ibid] Alternatively the reason is because one should not enter into Rosh Hashanah while he is oppressed. [M”E 581/38; See Admur 249/12 regarding Erev Shabbos]
Other Opinions: Some Poskim rule one is to fast until nightfall. [Teshuvos Maharil 33; Kneses Hagedola 581/7; Bach 562; Elya Raba 562/20; Conclusion of Kaf Hachaim 581/63]
 Machatzis Hashekel on M”A 581/10; brought in M”B 562/10; Piskeiy Teshuvos 581 footnote 128 that so is the custom today.
Other Opinions: Some fast until Plag Hamincha, and Daven Mincha before they break their fast. [Mateh Efraim 581/35; M”B 562/10] This however does not apply if one is weak in which case he may fast until Mincha Gedola. [Mateh Efraim 581/35] Kitzur SH”A [128/14] simply mentions fasting until Mincha.
 Machatzis Hashekel on M”A 581/10; Kitzur SH”A 128/14
 Machatzis Hashekel ibid; Rama 562/1 and M”A ibid
 Sheilas Yaavetz 2/147; Alef Lamagen 581/73; There he writes that it is not necessary to Daven Mincha prior to eating, rather as soon as it is midday he may eat.
 Alef Lamagen 581/73 in name of Yesod Veshoresh Havoda; Lekutei Mahrich [Aseres Yimei Teshuvah] in name of Yearos Dvash; Piskeiy Teshuvos 581 footnote 129
There he writes that certainly one should not daven privately before eating if he will be able to Daven with a Minyan later. Rather he should first eat and then Daven later with a Minyan. This applies even though one will no longer be able to say Aneinu in Mincha if he eats beforehand. Likewise if one will be unable to concentrate on his prayer then he is not Daven prior to eating, as this uproots the entire purpose of fasting. [ibid]
 Rama 581/2
 Other reasons: The Levush [brought in M”A 581/12] writes the reason why we eat before dawn even if one went to sleep the night before is because it is forbidden to fast on Erev Yom Tov. The M”A ibid questions this reason based on Taanis Bechoros. This reason of the Levush is also recorded in the Elya Raba 581/31. However see Mateh Yehuda; Kaf Hachaim 581/70; See Admur 249/12 “The Laws of Erev Shabbos” Chapter 5 Halacha 2!
 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 Kodesh 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 in which Admur rules it is permitted to eat a meal before 30 minutes before Alos and he completely omits this stringency of the M”A ibid brought from the Zohar.
 So is evident from M”A ibid; Beir Heiytiv ibid; and other Poskim; Igros Kodesh 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 Kodesh 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 Kodesh 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 Kodesh ibid]
 M”A 581/12; Elya Raba 581/20; Mateh Efraim 581/38
Does one need to do Hataras Nedarim in such a case? No. [M”A ibid; Degul Merivava Yoreh Deah 214/2; Yabia Omer 2/30] However some Poskim rule that one is to perform Hataras Nedarim if he cannot fast due to weakness. [Kaf Hachaim 568/46; 581/71; 589/34; Ben Ish Chaiy Netzavim 17; see Shach 214/2] Practically the Kaf Hachaim ibid concludes one is to do so if easily attainable.
 Halichos Olam 581/48 brought in Shevach Hamoadim footnote 15
 Rama ibid
 M”A 581/11; Mahril 44; Beis Yosef; Kneses Hagedola, brought in Kaf Hachaim 581/67
 Elya Raba 581/37
 M”A ibid “those that are relevant to the Bris”. This refers to the Baal Bris which is the father, Sandek and Mohel. [Machatzis Hashekel ibid; M”B 581/19]
 M”A ibid
 M”A 581/10; Elya Raba 581/34; M”B 581/17; Kaf Hachaim 581/65
 Rama 581/2
 Ben Ish Chaiy Netzavim 24; Kaf Hachaim 581/60