It is forbidden to cut one's nails on Shabbat, be it with a scissors or a clipper, by biting them with one's teeth, or by pulling them with one's hands. The Rishonim (early Medieval sages) debate the question of whether cutting one's nails is forbidden by Torah law, or by force of rabbinic enactment. Tosefot held that cutting one's nails falls under the category of "Melacha She'eina Tzericha Le'gufa" (literally, "an activity that is not required for its own sake"), since the individual does not remove the piece of nail because he needs that piece of nail. His intention is to remove and discard the nail, and not to keep it. And since Halacha follows Rabbi Shimon's view that this kind of Melacha (forbidden activity) is prohibited only by the Rabbis, and not by Torah law, cutting one's nails constitutes a Rabbinic, rather than Biblical, violation.
The Rivash (Rabbi Yitzchak Bar Sheshet Perfet, Spain-Algiers, 1326-1407), however, disagreed, and held that cutting nails indeed constitutes a Torah violation. He notes that the prohibition against cutting nails falls under the category of Gozez, shearing, which was performed during the construction of the Mishkan in preparing the animals' hides for tanning. There, too, the shearing was done not because the sheared material was needed, but rather for the needs of the surface – to prepare the leather. Therefore, cutting one's nails closely resembles the original Melacha, and is forbidden on the level of Torah law.
** See the Daily Halacha entitled: Sheering On Shabbat- Removing Hang Nails, Removing Band Aids, Combing Hair dated Dec. 19, 2004, for an exception on this rule.
The question arises whether a woman who must immerse in the Mikveh on the night of Shabbat may cut her nails before immersing. Generally, women are required to cut their nails before immersion so as to avoid the possibility of any dirt, dough or other substance being stuck in her nails, which would be considered a Chatzitza (interruption) between her body and the water, thus disqualifying her immersion. May a woman who must immerse on the night of Shabbat who forgot to cut her nails before Shabbat, cut her nails?
The Halacha is that a woman in such a case may not cut her nails, but she may ask a gentile to cut her nails for her. According to Tosefot, cutting nails is forbidden only on the level of Rabbinic enactment, and the prohibition of Amira L'nochri (instructing a gentile to perform Melacha on Shabbat) is likewise forbidden only by Chazal. And a basic rule in Halacha establishes that "Shevut De'shevut Be'makom Mitzva Mutar" – when two rabbinic prohibitions combine to render an action forbidden on Shabbat, that action is permissible when the performance of a Mitzva is at stake. Therefore, for the sake of properly immersing in the Mikveh, a woman may ask a gentile to cut her nails for her. And even according to the Rivash, who claims that nail-cutting constitutes a Torah violation on Shabbat, we can factor in as well the position of the Ba'al Ha'ittur (Rabbi Yitzchak of Marseilles, France, 1122-1193), that Amira L'nochri is permitted in all situations for the sake of performing a Mitzva. Thus, a woman who must cut her nails on Shabbat to immerse in the Mikveh may ask a gentile to cut her nails.
According to the Taz (Rabbi David Halevi, Poland, 1586-1667), in such a case, where a woman has a gentile cut her nails, she should not give her hand to the gentile, as this would amount to active involvement in the Melacha. Instead, she should have the gentile take her hand and then cut her nails. Chacham Ovadia Yosef rules that strictly speaking it is permissible for the woman to give her hand to the gentile, though it is preferable to be stringent in this regard.
This applies as well to hair combing, which is also required before immersion, in order to undo knots in the hair which would constitute a Chatzitza. Combing hair is forbidden on Shabbat (see above noted Halacha entitled “Sheering On Shabbat- Removing…” for exception), and therefore a woman who must comb her hair to immerse in the Mikveh on Shabbat should ask a gentile to comb her hair for her.
Summary: It is forbidden to cut one's nails on Shabbat. If a woman must immerse in the Mikveh on Friday night and did not cut her nails before Shabbat, she should ask a gentile to cut her nails for her. In such a case, she should preferably not actually give her hand to the gentile, and rather let the gentile take her hand. Similarly, a woman who must immerse on Friday night and did not comb her hair before Shabbat should ask a gentile to comb her hair for her.
