The “Unknown Days” of the Jewish Calendar


siddurBy Rabbi Yehuda Spitz

This week, an unsuspecting person wishing to catch a minyan, who walks into a random shul in many places around the world, might be in for a surprise. After the Shemoneh Esrei prayer on Sunday there was no Tachanun; on Monday there was Selichos, and on Thursday, again no Tachanun! Why would this be? No Tachanun generally signifies that it is a festive day; yet, no other observances are readily noticeable. As for the reciting of Selichos on Monday, they are usually reserved for a fast day; yet no one seems to be fasting! What is going on?

The answer is that three separate specific “Unknown Days” happen to fall out on during this apparently chock-full week.

Pesach Sheini

The first of these days, Sunday (14th of Nisan), is dubbed ‘Pesach Sheini‘, which commemorates the day when those who were unable to bring the annual Korban Pesach (special Pesach sacrifice – Pascal lamb) at its proper time (Erev Pesach), were given a second chance to offer this unique Korban. Although technically not considered a real holiday, and despite the fact that it is (astonishingly!) not listed in the traditional Halachicsources as one of the days that Tachanun is not said, nevertheless, the custom for many is not to say Tachnun on Pesach Sheini, in order to ‘tap into’ the merit that this particular day had during the times of the Beis HaMikdash.


The second of these days, Monday, is actually the third and last day in a semi-annual series of “Days of Tefilla” colloquially known as BeHa”B. This acronym stands for Monday (Beis – 2nd day of the week), Thursday (Hei – 5th day of the week), and the following Monday (Beis). These days are observed on the first Monday, Thursday, and Monday following the earliest Rosh Chodesh after Pesach (Rosh Chodesh Iyar), and likewise after Sukkos (Rosh Chodesh Cheshvan). The custom of utilizing these specific days for Prayer and supplication is already mentioned almost 900 years ago by the Baalei Tosafos, its importance reiterated by the Tur, and unbeknownst to many, actually codified in Halacha by the Shulchan Aruch as a properminhag!

The most commonly mentioned reason why these days of prayer are following the holidays of Pesach and Sukkos, is that over the extended holidays, when there is extensive feasting and simcha, it is more likely that people may have stumbled in some area due to improper behavior and inadvertent sin, and BeHa”B is meant to help rectify any possible offense.

Other explanations offered to explain why BeHa”B was established include:

1.      To entreat G-d to strengthen our bodies especially at the time of changing seasons when many are likely to get sick.

2.      To beseech G-d that we should have abundant harvests (after Pesach) and rains (after Sukkos).

3.      To commemorate Queen Esther’s original 3-day fast (which actually was Pesach time, and not Purim time).

Yet, although BeHa”B is traditionally meant to be a fast day, still, very few actually do fast, as in our generations people are considered weaker.  In addition, because it is based on a minhag and not a Biblical source, many make do with Selichos instead. That is why our fellow walking in would not see any other traditional signs of a fast day.

Lag B’Omer

The third of these ‘Unknown Days’ with no other obvious observances during davening except the omission of Tachanun, is Lag B’Omer [18th of  Iyar]. In Israel, this quasi-holiday is widely celebrated, with over half-a million people converging on the sleepy town of Meron to visit the grave of Rabi Shimon Bar Yochai, as well as tens of thousands visiting the grave of Shimon Hatzaddik in Yerushalayim. With enormous bonfires seemingly on almost every street corner, Lag B’Omer in Israel has unfortunately become a pyromaniac’s delight and the firefighter’s and asthmatics’ nightmare. Yet, in most of Chu”tz La’aretz, there is no other real commemoration or observances of this special day, unless one counts the “traditional” game of baseball and subsequent barbeque. So, it is quite possible that our clueless colleague might just wonder about the omission of Tachanun on Lag B’Omer.

Hopefully, by showcasing these relatively “Unknown Days”, this article should help raise awareness of them and their customs, and change the attitude of “another ho-hum mediocre week of the Jewish Calendar” to the realization of an exciting jam-packed one!


This article originally appeared on the Ohr Somayach website:

For any questions, comments or for the full Mareh Mekomos / sources, please email the author:

Rabbi Yehuda Spitz serves as the Shaul U’ Meishiv and Rosh Chabura of the Ohr Lagolah Halacha Kollel at Yeshivas Ohr Somayach in Yerushalayim. He also currently writes a contemporary halacha column for the Ohr Somayach website titled “Insights Into Halacha“.

For a further discussion as to the importance of reciting Tachanun, see previous article “Tachanun in Yerushalayim“.

See Sefer HaToda’ah (vol. 2, pg. 253) who explains that it is called this as it is the Pesach that falls out in the second month of the year – Iyar. In the Mishna and Gemara (ex. Rosh Hashana 18a) it is referred to as “Pesach Kattan” or “Pesach Ze’ira” (the Small Pesach).

Bamidbar (Beha’aloscha) Ch. 9, verses 1 – 15. See Rashi ad loc. verse 10 and Sefer HaChinuch 380.

The Aruch Hashulchan (O.C. 131, 12) writes that he is astounded that Pesach Sheini is not listed by any of the traditional Halachic sources  – [including the Gemara, Rambam, Tur, Shulchan Aruch, or even the Mishna Berura!] as one of the days that Tachanun is not said.

Although the Pri Megadim (O.C. 131 M.Z. s.v. mah) maintains that Tachanun should be said on Pesach Sheini – as the original day it is commemorating was only meant for individuals in unique circumstances, and its absence of mention in the traditional Halachic sources as one of the days that Tachanun is not said speaks volumes, nevertheless, many rule that one should not say Tachanun on this day including (ad loc.) the Knesses HaGedolah (Haghos B.Y. 12, citing ‘Minhag Salonika’), Pri Chadash (7), Ya’avetz (in his Siddur Beis Yaakov), Shalmei Tzibur (10), Sha’arei Teshuva (19), Beis David (Shu”t 53), Butchatcher Rav (Eshel Avraham s.v. nohagin), Shulchan HaTahor (8), Aruch Hashulchan (ibid.), and the Kaf Hachaim (99). This is also the “Minhag Yerushalayim” – see the Tukachinsky Luach. However, it is known that the Chazon Ish did say Tachanun on Pesach Sheini (sefer Bein Pesach L’Shavuos, in the introduction to the sefer titled ‘Hanhagos HaChazon Ish’ by Rav Chaim Kanievsky).

Eshel Avraham ibid. There is another common custom associated with Pesach Sheini – eating Matzah (see Sefer HaToda’ah vol. 2, pg. 253; Shu”t Rivevos Efraim vol. 2, 129, 39 & vol. 3, 331; and Shu”t Divrei Shalom vol. 4, 87); but that is not noticeable in shul!

Monday and Thursday are considered especially potent days for prayer, as Moshe Rabbeinu climbed Har Sinai to receive the Torah on a Thursday and returned with it on a Monday [Midrash Tanchuma (Parshas Vayera 16), Tosafos Bava Kamma (82b s.v. kday shelo), Mishna Berura (134, 6)]. A mnemonic to showcase this is the first pasuk read on a public fast day Haftara (Yeshaya Ch. 55, verse 6) “Dirshu Hashem B’Himatzo” – “Seek out G-d when He is to be found”. The letters Beis and Hei show that an auspicious time when G-d may be found is on Monday and Thursday – Matteh Moshe (748). See also Shulchan Aruch (O.C. 560, 3, based on Tosefta Ta’anis Ch. 2, 5) and Tur, Shulchan Aruch and Rema (O.C. 134, 1) that Mondays and Thursdays are preferable for fasting and prayer.

Tosafos Kedushin 81a s.v. sakva.

Tur O.C. 492, who refers to BeHa”B as a French-German custom.

Although both the Tur and Rema call BeHa”B a German-French custom, and the Shulchan Gavoah (O.C. 492, 1, cited in Kaf Hachaim 492, 8) writes that this was not the minhag in Spain (additionally mentioned in the Sefer HaToda’ah vol. 1, pg 157 and Kitzur Shulchan Aruch of Rav R.B. Toledano vol. 4, 330), implying that Sefardim are not beholden to keep BeHa”B, nevertheless, it must be noted that the Shulchan Aruch himself must have felt strongly about this minhag of BeHa”B, as aside for spending a whole siman on it – O.C. 492, he also refers to it and its importance in at least two other locations – O.C. 429, 2 and 566, 2 – 4. Later Sefardic authorities as well, including the Knesses HaGedolah, Pri Chadash and Chida (ad loc.) also discuss its importance. Therefore, this author finds it interesting that the general Sefardic minhag is not say BeHa”B. In fact, the Siman referring to BeHa”B – O.C. 492, is noticeably absent from the Yalkut Yosef’s Kitzur Shulchan Aruch, implying that it is not relevant to the average Sefardi. However, the Taz (O.C. 566, 3) does note that already in his time (and among Ashkenazic communities) BeHa”B observance was not widespread. See Shu”t Mishneh Halachos (vol. 3, 15, s.v. u’lfa”d), who, as a side point to the issue being addressed in his responsum, maintains that one who does not observe BeHa”B is not considered “Poresh Min HaTzibbur“.

The Sha’arei Teshuva (492, 1) cites the Ra’avad (Tamim Dayim 177) who maintains that “Yechidim and Anshei Ma’aseh” should keep a BeHa”B after Shavuos as well; yet concludes that the prevailing custom is not to. See also Beis Yosef (end O.C. 429), Chok Yaakov (492, 1), Shulchan Aruch HaRav (O.C. 492, 1), Magen Avraham (ad loc, 1), Levush (ad loc, 1), Pri Megadim (E.A. ad loc, 1), Chida (Birkei Yosef ad loc, 1), Kaf Hachaim (ad loc, 1) and Mishna Berura (ad loc, 1), who all rule that there is no BeHa”B after Shavuos.

See Tur (O.C. 492), Rema (ad loc), Magen Avraham (ad loc, 1), and Mishna Berura (ad loc, 1). This idea is based on Iyov (Ch. 1, verse 5) who would bring Korbanos after “Y’mei Mishteh”. These sins might be due to mingling (at a festive meal or even at a Drasha in the Synagogue (!) – Rashi & Tosafos – Kiddushin 81a s.v. sakva), Yom Tov and Chol Hamoed related transgressions (Elyah Rabba 492, 3, citing the Ma’aglei Tzedek), Chilul Hashem (Tur O.C. 429, 2), or overabundance of merriment (Mahari”l, Dinei Hayamim Bein Pesach L’Shavuos) and gastronomical pleasures (Kol Bo).

Levush O.C. 492, 1.

Ra’avyah (Ta’anis 863), Mordechai (Ta’anis, 629), Shach (Y”D 220, 31 s.v. v’nirah li), Sefer HaToda’ah (vol. 1, pg. 156).

Sefer Minhagei Yisrael (vol. 1, Ch. 26). [He opines that the reason for the BeHa”B after Sukkos is not for the same reason as the BeHa”B after Pesach.] The Ta’anis Esther that we fast before Purim is not really due to Esther’s actual fast as recorded in the Megillah, but rather to commemorate that when the Jews went to war against the anti-Semites of their day, they fasted (see Mishna Berura 686, 2, quoting the Rambam – Hilchos Ta’anis Ch. 5, 5).

Shu”t Chavos Yair (126), Aruch Hashulchan (O.C. 492, 2), Mishna Berura (566, 6), Shu”t Mishneh Halachos (vol. 9, 174). See also Shu”t Noda B’Yehuda (Kamma O.C. 35, s.v. hinei) and Shulchan Aruch HaRav (Iggeres HaTeshuva Ch. 3, based on the Yerushalmi Nedarim Ch. 8, 1).

It is customary among many to also recite Avinu Malkeinu.

See Tur/ Shulchan Aruch and Rema and relevant commentaries to O.C. 131, 6, and 493, 2. There are several reasons offered for why Tachanun is not said on Lag B’Omer, including: It’s the day when Rabbi Akiva’s 24,000 students stopped dying (See Biur HaGr”a O.C. 131, 6 s.v. b’Lag and Pri Megadim O.C. 493, M.Z. 1); It’s the day when the Mann (manna) started to fall, feeding Bnei Yisrael in the Sinai desert (Shu”t Chasam Sofer Y”D 233, s.v. amnam yada’ati); It is the day when Rabi Shimon bar Yochai and his son, Rabi Elazar came out of the cave they hid in for 13 years (see Aruch Hashulchan O.C. 493, 7); It is Rabi Shimon bar Yochai’s Yahrtzeit (see Birkei Yosef O.C. 493, 4, Aruch Hashulchan ibid. and Kaf Hachaim ad loc. 27; however, this might actually be based on a printing mistake! See below for Rabbi Eliezer Brodt’s relevant article); It is the day when Rabi Akiva gave Semicha to his remaining five students (including Rabi Shimon bar Yochai) after 24,000 died, allowing the Torah’s mesorah to perpetuate (Yalkut Me’am Loez – Parshas Emor); It is the day when Rabi Shimon bar Yochai’s (hidden) Torah (Zohar) became revealed to the world (Zohar – Parshas Ha’azinu). There are many sefarimavailable who give full treatment to the topic of Lag B’Omer, including Bein Pesach L’Shavuos and Nitei Gavriel. It is also worthwhile to read Rabbi Eliezer Brodt’s excellent articles on topic: and

As per the custom mentioned by Rav Chaim Vital in Sha’ar HaKavannos; see Ateres Zkainim (O.C. 493, 1), Aruch Hashulchan (O.C. 493, 7), and Kaf Hachaim (O.C. 493, 26). However, there were several authorities who were skeptical at best about this custom, including the Chasam Sofer (Shu”t Y”D 233, s.v. amnam yada’ati) and the Shoel U’Meishiv (Shu”t vol. 5, 39). See also Shu”t Yechaveh Daas (vol. 5, 35). For a discussion as to the level of Rabi Shimon bar Yochai’s greatness, see Rabbeinu Chananel’s commentary to Sukkah 45b.

In sefer Bein Pesach L’Shavuos (pg. 302) it mentions that the custom in Krakow, Poland was to visit the famed Rema’s grave on Lag B’Omer, as it is his Yahrtzeit.

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  1. “Unknown days”? Unknown to whom? Seriously? I’m really not understanding the point of this article.

  2. Thank you matzav for posting this elucidating article! i never realized how much was behind these days – especially the behab that no one wants to (or doesn’t) say! keep up the good work

  3. The shul I went to this week says no Tachnun this whole week. They sat its “hoid”. Can you explain that to me?

  4. Ohev shalom,
    – unless its irony, i’m not good with irony.

    either way make note of the source of the article and then take note of the fact that not everyone is as erudite as you… this is, after all a publicly accessible site.

  5. If you were a real ohev shalom you’d realize that there are millions of jews who unfortunately dont know about these days on the calendar.

    Perhaps, in the spirit of sefiras haomer, if all yidden reached out to their fellow brethren and showed that they care and how beautiful it is to be part of klal yisroel – you’re right, this article wouldn’t be necesary.

    Furthermore, a bisel chazara of even pashut inyanim never hurts…aino domeh mi she’shoneh mea pa’amim l’mi she’shoneh mea v’ achas….

  6. Thank You Rabbi Spitz for this article. Although myself and others are well aware that these days do exist in the Jewish calender, much of the background/halachics about them are unknown. The extensive footnotes are always my favourite part of your articles and where I learn the most from. I wish I had the time to look them all up!

  7. to # 1 (ohev shalom – a misnomer if i have ever heard one)- I, as an avid reader of matzav, do not understand your comment. obviously people heard of these days, the point (i assume) of this comprehensive article here was to showcase what they are really all about and various aspects of them. I for one (although probably not the gadol hador you seem to be claiming you are) learned a large amount from this article. kudos for sharing matzav!