...אָמַר רַב שֵׁשֶׁת: שֵׂעָר בָּאִשָּׁה עֶרְוָה, שֶׁנֶּאֱמַר: ״שַׂעֲרֵךְ כְּעֵדֶר הָעִזִּים״.
...Rav Sheshet stated: Even a woman’s hair is considered nakedness, for it too is praised, as it is written: “Your hair is like a flock of goats, trailing down from Mount Gilead” (Song of Songs 4:1).
שו”ת מהר”ם אלשקר סימן לה
וההיא דשער באשה ערוה לא מיירי אלא בשער שדרך האשה לכסותו…בפרק חזקת הבתים דאמרינן התם עושה אשה כל תכשיטיה ומשיירת דבר מועט. מאי היא? רב אמר בת צדעא …וזה המנהג בעצמו הוא מנהג הנשים היום שהאשה קולעת כל שערה ומשיירת שער הצדעים יורד על פניה והוא הנקרא בלשון חכמים בת צידעא כמו שנתבאר … הקילו רבותינו ז”ל כדי שלא תתגנה האשה על בעלה
Responsa Maharam Alashkar 35 (Egypt, 15th-16th centuries)
This statement that “the hair of a woman is erva” only deals with hair that a woman’s practice is to cover…In the [Talmud] chapter Chezkat Ha-batim, we say, “a woman does all her adornments and leaves out a little bit.” What is it [that she leaves out]? Rav says ‘bat tzida’” …This is the very custom of women today, that the woman binds all her hair and leaves out hair at the temples going down beside her face and this is called in the language of our sages ‘bat tzida,‘ as was explained…Our sages were lenient in many matters, so that a woman would not become unappealing to her husband.
§ The mishna teaches: Absalom was excessively proud of his hair, and therefore he was hung by his hair. The Sages taught (Tosefta 3:16): Absalom rebelled and sinned due to his hair, as it is stated: “Now in all Israel there was none to be so much praised as Absalom for his beauty; from the sole of his foot even to the crown of his head there was no blemish in him. And when he shaved his head, as it was at every year’s end that he shaved it; because the hair was heavy on him, therefore he shaved it, and he weighed the hair of his head at two hundred shekels, by the king’s stone” (II Samuel 14:25–26). What is the king’s stone? The Sages taught: A stone with which the people of Tiberias and the people of Tzippori weigh items. The baraita continues: And since he was proud of his hair, therefore, he was hung by his hair, as it is stated in the verse describing the battle between the forces of David and Absalom: “And Absalom chanced to meet the servants of David. And Absalom was riding upon his mule, and the mule went under the thick boughs of a great terebinth, and his head caught hold of the terebinth, and he was taken up between the heaven and the earth; and the mule that was under him went on” (II Samuel 18:9). After he was spotted by the opposing troops, Absalom took a sword [safseira] and wanted to cut his hair to save himself. The school of Rabbi Yishmael taught: At that moment, the gates of the netherworld opened beneath him and he was afraid to fall into it, so he did not cut his hair, and he was killed by the opposing troops.
(א) תער לא יעבור על ראשו ובזה ישליך אחרי גוו כל מחשבת יופי ותיקון שער:
(1) תער לא יעבור על ראשו, by not coiffing his hair through trimming it to certain shapes, he automatically abandons all manner of preening himself.
(א) דינים הנוהגים בימי העומר. ובו ד' סעיפים:
נוהגים שלא לישא אשה בין פסח לעצרת עד ל"ג בעומר מפני שבאותו זמן מתו תלמידי ר' עקיבא...
(ב) נוהגים שלא להסתפר עד ל"ג לעומר שאומרים שאז פסקו מלמות...
(1) It is customary not to get married between Pesach and Shavuot, until Lag BaOmer (the 33rd day), because during that time, the students of Rabbi Akiva died... (2) It is customary not to cut one's hair until Lag BaOmer, since it is said that that is when they stopped dying...
(ז) שַׁבָּת שֶׁחָל תִּשְׁעָה בְאָב לִהְיוֹת בְּתוֹכָהּ, אָסוּר מִלְּסַפֵּר וּמִלְּכַבֵּס
(7) During the week in which the Ninth of Av occurs, it is prohibited to cut one’s hair and to launder clothes
Donating hair on the three weeks: She’ela, Teshuva (https://www.matan.org.il/en/qna/donating-hair-on-the-three-weeks/)
She'ela (Question)
Can I donate my hair to Zichron Menachem (to make wigs for children with cancer) during the three weeks? I want to do it in honor of my mother’s Yartzeit which is 24th of Tammuz.
Teshuva (Responsum) from Rabbanit Surale Rosen
The earliest reference we have is ספר המנהגים לרבינו אייזיק טירנא (app. 1400) where he brings the minhag not to have a hair cut from 17th of Tammuz till after Tisha B’Av. The Remah in Orach Chayim 551:4 mentions this Ashkenazi custom together with the minhag not to wash clothes from Rosh Chodesh Av as opposed to the Shulkhan Arukh who rules that it’s only on the actual week of the fast…
The prohibition to have a haircut during the entirety of the 3 weeks is not explained but the Remah brings it as הלכה למעשה that we know has been kept for generations. Therefore, I would advise you to cut your hair before 17th of Tammuz and then make the actual donation on the date of your mother’s Yahrzeit.