(This should not be relied upon for practical halacha. When a question arises a Rabbi should be consulted.)
1.The Rama, citing the Avudraham, writes that one should not cut their nails in order, as this leads to poverty, forgetfulness and r”l the loss of one’s children (Darkei Moshe 241). Rather, they should cut them in the following order: On one’s left hand he should first cut the nail of his ring finger, then index finger, then pinky, then middle, and finally thumb (4,2,5,3,1). On one’s right hand he should begin with cutting the nail of his index finger, then ring, then thumb, then middle, and finally pinky (2,4,1,3,5). (Rama 260 see also Shu”t Bitzeil Hachochma 3:53)
2. The Tehila L’David (260:2) and the Aruch Hashulchan (260:6) comment that although the Rama implies that one should first cut the fingernails on the left hand before the right hand that is not so and one should cut the right hand’s nails first. However, they cite the Kol Bo who writes that one should cut the left fingernails before the right fingernails.
3. According to the Chazon Ish one only needs to perform the above prescribed order when cutting one’s fingernails. However, one may cut one’s toenails in any order that one wishes (Sefer Hazicaron Rav Chaim Kanievsky shlit”a). This is also the view of Harav Chaim Naeh zt”l. (Ketzos Hashulchan 73:7)
4. The Arizal, however, was not careful about this matter, and would cut his fingernails in order, one after another. Although, the Magen Avraham and the Mishnah Berurah write that one should nevertheless act stringently in accordance with the ruling of the Rama, the Chida (Birkei Yosef 5) disagrees and rules that if the Arizal was not cautious about these matters, surely there must not be any danger involved. Therefore, one may rule leniently and one cuts his nails in order, one after another. For normative halacha, a rav should be consulted.
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