The Three Weeks - Haircuts
According to Ashkenazi custom, the three weeks between the seventeenth of Tammuz and Tisha B'av are observed as a period of mourning in memory of the destruction of the Beit Hamikdash.[1] The seventeenth of Tammuz was considered to be an appropriate time to begin the mourning practices as it was on that day that the daily offerings ceased to be brought in the Beit Hamikdash.[2] So too, it is also the date that the walls of Jerusalem were breached by the enemy culminating with its destruction three weeks later.[3] This three week period is referred to as "Bein Hametzarim" meaning, "Between the Troubles".
Although there are a number of mourning-like restrictions which are observed during this period, among the more noticeable of them is the prohibition to cut one's hair. For men, this usually includes shaving, as well. Sefardic practice is only to prohibit haircutting during the week in which Tisha B'av falls.[4] Sefardim who find themselves living among Ashkenazim who don't shave are not required to conform and may continue to shave as normal.[5] A number of Ashkenazi authorities allow one to shave in honor of Shabbat during the three weeks.[6]
There are a number of exceptions to the prohibition on shaving during the three weeks. For example, one is permitted to trim one's moustache if it interferes with eating.[7] Similarly, one whose beard causes him extreme discomfort may be permitted to shave, as well.[8] One who completes the period of mourning for a parent during the three weeks is permitted to take a hair cut.[9] So too, one who is making a brit during the three weeks is permitted to take a haircut in honor of the occasion. This includes the father of the baby, the mohel, and the sandak.[10] It is best that parents refrain from giving their children haircuts during the three weeks as well,[11] especially during the week in which Tisha B'av falls.[12] Most authorities permit one to trim one's nails without reservation.[13]
One who is concerned that an untidy and unattractive appearance from not shaving will compromise the stability of one's employment is permitted to shave. Nevertheless, one is expected to endure the minor social discomfort that comes with an unkempt appearance.[14] Although the prohibition on haircutting applies equally to women, they are permitted to shave as normal. This is because the purpose of the restrictions are to convey a feeling of mourning, not one of repugnance.[15] As such, one can and should maintain a dignified appearance including brushing one's hair, teeth, and wearing proper clothing during this time.[16]
[1] Rema, OC 551:2.
[2] Rambam, Hilchot Taanit 5:2.
[3] Taanit 28b.
[4] OC 551:3.
[5] Yechaveh Daat 4:36.
[6] She'arim Metzuyanim B'halacha 122:5; Biur Halacha 551:3; Kaf Hachaim, OC 551:66; Nefesh Harav pg. 191; Chatam Sofer, YD 348.
[7] OC 551:13.
[8] She'arim Hametzuyanim B’halacha 122:5.
[9] Be'er Heitev, OC 551:18; Mishna Berura 551:87.
[10] Chatam Sofer, OC 158.
[11] Shaar Hatziun 551:91; Elya Rabba 551:28.
[12] OC 551:14.
[13] Magen Avraham 551:11; Kitzur Shulchan Aruch 122:5.
[14] Igrot Moshe, OC 4:102; CM 1:93.
[15] Piskei Teshuvot 551:43, Rivevot Ephraim 5:376:2.
[16] Mishna Berura 551:20.