One should be sure to trim one's fingernails each week before the arrival of Shabbat in order to ensure that one has a pleasant appearance in honor of Shabbat.[1] It is interesting to note that anytime one trims one's fingernails one should preferably not do so in a finger-by-finger order.[2] The suggested order for the left hand is: the fourth finger followed by the second, fifth, and third fingers, concluding with the thumb. When cutting the nails of the right hand the order is: the second finger followed by the fourth finger, then the thumb, then the third finger and concluding with the fifth finger.[3]

It is best not to trim one's fingernails on a Thursday, as we are told that fingernails begin to re-grow three days after having been cut, which would be on Shabbat.[4] There are two reasons offered as to why one should avoid causing one's nails to begin growing on Shabbat: 1. lest it appear as if one is coordinating for a forbidden activity to take place on Shabbat and 2. it is said that fingernails cease to appear nice and tidy when they begin growing back.[5] Those who are in the habit of biting their fingernails must be sure not to do so on Shabbat as it is a violation of the melacha of gozez.[6]

None of this applies to toenails, which one may trim at anytime and in any order.[7] One should not, however, cut one's fingernails and toenails on the same day.[8] We are taught that one should not allow one's fingernails to get too long because there is a spirit of impurity which attaches itself to the ends of long nails.[9] One should ensure that no fingernail and toenail clippings fall to the floor as they are said cause miscarriages.[10] Any fingernails which do fall to the floor should be promptly swept away.[11] In a place where no women are to be found one need not be overly concerned if some nail clippings inadvertently fall to the ground.[12]

One must wash one's hands after cutting one's fingernails or toenails.[13] One should either flush nail clippings down the toilet,[14] burn them, or bury them.[15] We are taught that a special reward is reserved in Heaven for those who make the effort to ensure that their hair and nails are always trim and tidy in honor of Shabbat.[16]

[1] O.C. 260:1

[2] Kaf Hachaim 260:17

[3] Rema O.C. 260:1

[4] Mishna Berura 260:6

[5] Kaf Hachaim 260:15

[6] O.C. 340:1 Mishna Berura 340:1

[7] Ketzot Hashulchan 73:7

[8] Mishna Berura 260:1

[9] Kaf Hachaim 260:9

[10] Mo'ed Katan 18a.

[11] Pitchei Olam 260:4

[12] Pitchei Olam 260:4

[13] O.C. 4:18, Piskei Teshuvot 4:21

[14] Ben Ish Chai;Lech Lecha

[15] Nidda 17a

[16] Kaf Hachaim 206:16