To purchase this Sefer, click here
In previous times it was only obligatory to wear a Yarmulke upon reciting Hashem’s name or, according to some opinions, when inside a Shul, as will be explained. It was a mere act of piety to wear a Yarmulke during other times. However today it is an obligation to wear a Yarmulke at all times. One may not walk, or even sit, with one’s head uncovered. [This applies even when one is under a roof. One who does not wear a Yarmulke today is considered rebellious and brazen.]
When reciting a blessing: It is forbidden for one to utter any of G-d’s names without a head covering. This applied even in previous times.
Inside a Shul: Some opinions rule it is forbidden to enter into a Synagogue without a head covering, and that this applied even in previous times. They say one is to protest against one who does so.
Is one to wear a head covering while he is sleeping?
Yes. It is an act of piety to cover the head even during one’s sleep. This applies even to children as will be explained next. [One is thus to try to sleep with a large Yarmulke or make some other arraignment to ensure that his Yarmulke does not fall off during his sleep.]
May one learn Torah without a Yarmulke?
May one think Torah without a Yarmulke?
Yes. Thus if one removed his Yarmulke during a haircut he may think Torah in the interim.
May one mention the word Shalom without a head covering, such as to say Shalom Aleichem?
The Shapiro brothers of Slavita:
The great Tzaddik and student of the Baal Shem Tov, Harav Pinchas Koretzer, had two grandsons, Shmuel Avraham and Pinchas Shapiro of Slavita. They inherited their father’s printing press in Slavita which was one of the most foremost sources of Jewish print in those times. A group of informers caused the brothers to be incarcerated by the Russian authorities. The brothers were tortured in the most treacherous of manners. The climax of their ordeal was when they were forced to pass through two lines of soldiers, who heavily beat them until they reached the other side. It occurred that the younger brother lost his Yarmulke while walking through the path and he stood still, refusing to budge even a step forward without a head covering, despite this causing him to continuously receive the lashings. The brothers were eventually released in a miraculous manner and became famous for their self sacrifice that they showed for Hashem and His religion. Their exemplification of Mesirus Nefesh is conserved within their Niggun which is known as Niggun Slavita.
 Basra 2/6; Taz 8/3; M”B 2/11; See Measef Lechol Hamachanos 2/21; Yabia Omer 9/1; Piskeiy Teshuvos 2/9; For a thorough analysis on the obligation See Piskeiy Dinim Tzemach Tzedek 1-8
Ruling of Kama: In Kama 2/7 Admur implies that walking four cubits with a revealed head is forbidden according to law. However in 91/3 Admur rules even walking more than four Amos is merely an act of piety, and so is implied from 46/2. See next footnote.
Talmudic sources: In Kedushin 29b it says that only after marriage would they wear a kerchief on their heads and not walk bare headed. In Kedushin 33a it implies that one should cover his head in honor of Torah scholars. [However perhaps these Gemara’s are only referring to wearing a covering on top of the first covering, as will be brought below regarding wearing a hat over ones yarmulke. This also seems logical as otherwise it would create contradictions with other places in the Talmud which state that one must wear a covering over his head.] In Shabbos 156 it states that the mother of Rebbe Nachman Bar Yitzchak was careful to cover his head even when he was a small child.
Ruling of Rashal: The Rashal [Teshuva 72; brought in Beir Heiytiv 2/6] rules that it is not necessary from the letter of the law to cover one’s head when he is under a roof.
Opinion of Michaber: The Michaber 2/6 rules one may not walk four Amos with a revealed head. In the Beis Yosef 46 he clearly writes that this is forbidden from the letter of the law. [Piskeiy Dinim ibid; Unlike Machatzis Hashekel 2/6 in Michaber] So also is understood from M”A 2/6 and M”B 2/11 to be the opinion of Michaber.
Opinion of Zohar: The Zohar writes that walking four Amos with a head covering is a requirement only for Torah Scholars. [Kaf Hachaim 2/15]
Summary of opinions: The following Poskim rule wearing a head covering is required from the letter of the law: Taz 8/3 [always; however see Taz Yoreh Deah 242/11]; Basra 2/6 [always]; M”B 2/11 [always] Mateh Yehuda 2/10; Nivei Shalom 2/4; Yad Ahron; Kitzur SH”A 3/6 [walking four Amos]. The following Poskim rule wearing a head covering is always a mere act of piety: Bach; Olas Tamid 2/5; Kama 91/3; Machatzis Hashekel ibid; Mamar Mordechai 91/5; Birkeiy Yosef 2/2. The Kaf Hachaim 2/15 concludes like the Zohar that for layman walking with a head covering is an act of piety.
 91/3; M”A 2/6
Was it an act of piety to wear a Yarmulke even when sitting and was it only an act of piety to wear it when walking more than four Amos? In Basra 2/6 and Kama 91/3 Admur rules that it was an act of piety not to walk four Amos with an uncovered head. This implies that it was not necessary, even due to piety, to wear a Yarmulke in other instances, such as when walking less than four Amos, or when sitting down, and that even when walking four Amos it was merely an act of piety. Likewise in 46/2 Admur rules there is no prohibition from the letter of the law to not cover the head. However in Kama 2/7 Admur rules that “One may not walk four Amos with an uncovered head, and it is an act of piety not to walk even less than four Amos, and not to even sit, with an uncovered head.” This implies that walking four cubits with a revealed head is forbidden according to law, and the attribute of piety only relates to not walking even less than four cubits without a head covering. [Piskeiy Dinim ibid, as rules Beis Yosef 46 and implied from Michaber 2/6; and so rules Ketzos Hashulchan 3 footnote 8; so also rules Taz Yoreh deah 242/11] Vetzaruch Iyun as 91/3 is part of the Mahadurah Kama and there is thus a contradiction between Kama 4/7 and Kama 91/3. [The above contradiction is also apparent in the rulings of the M”A 2/6 and 91/3. This contradiction is mentioned in Ketzos Hashulchan 3 footnote 8; The Machatzis Hashekel 2/6 explains [in the M”A] that in truth there is no contradiction and even walking more than four Amos is only a Midas Chassidus and it is “Lav Davka”. However this is not possible to explain in Admur which brings both laws of less than four Amos and four Amos together. Likewise the Piskeiy Dinim learns from the wording 2/7 that it is forbidden from the letter of the law. Vetzaruch Iyun.]
Driving or riding in a car or bus without a Yarmulke: One who is driving a car or being driven in a car or bus is considered to be walking four cubits. Hence even in previous times it was required to wear a Yarmulke while on a wagon. [Taz Yoreh Deah 242/11] However according to other Poskim mentioned above even walking four Amos was merely an act of piety.
 Basra ibid; Taz ibid and all the Poskim mentioned in previous footnotes.
The reason: In earlier times it was very common for the majority of people to at times walk around bare headed due to the heat. Hence it was [only] an attribute of piety to not walk four cubits [6 feet 4 inches] without ones head covering, [and was not required by law.] Today however that it is common for everyone to cover their head, it is always forbidden to walk or even sit with one’s head uncovered as by doing so one reveals an area of the body which is commonly covered, and this is immodest. Furthermore in today’s times that the gentiles walk bareheaded while the Jews which are holy cover their head due to modesty, certainly it is an obligation for one to cover his head, and one who walks or even sits without a head covering transgresses the command of “In their statutes do not follow”. [Basra 2/6]
 Pashut, unlike Rashal ibid
 See Taz 8/3 based on Gemara; Chidushei Chasam Sofer Nedarim 30; It is said in the name of the Chasam Sofer as follows: One who walks without a Yarmulke is not a “Sheigetz” due to walking without a Yarmulke. Rather since he is a “Sheigitz” therefore he walks without a Yarmulke. [Beir Moshe 8/40]
 Basra 2/6; 91/3
 Kol Bo 11
 Shlah 198 and so rules Elya Raba 2/4; M”B 2/11; Shulchan Hatahor [brought in Piskeiy Teshuvos 2 footnote 62] writes that sleeping with an uncovered head allows Kelipos to receive sustenance at night. There is a story told of the Rebbe Rayatz that he once saw one of the Yeshiva Bochurim sleeping without a Yarmulke [due to it falling off during his sleep] and he asked the student to leave the Yeshiva. Mashpim explain the reason for this is because a Torah student should be trained to have subjugation to G-d even during his sleep. It requires further research for the exact details and accuracy of this story.
 Shulchan Hatahor Tznius 4
 M”B 2/12
 Piskeiy Teshuvos 2/10 in name of today’s Poskim.
 Igros Moshe 4/40; Halichos Shlomo 2/16; Yabia Omer 6/15
 Brought in Seder Hadoros of Baal Shem Tov p. 13
 Tradition states that the brothers had a gentile drunkard working in their print house. The gentile committed suicide in the printing press and was discovered there. The brothers were accused with his murder.
 It is told that the brothers sang this Niggun while going through the line of soldiers. It is what helped them receive the suffering in happiness. Reb Mendal Futerfas was very fond of this Niggun and would drop buckets of tears while singing it. [Heard from Harav Chaim Shalom Deitch]