بسم الله الرحمن الرحيم
Wearing fake (manufactured) nails or allowing the toe and fingernails to grow long opposes the natural disposition, just as its clarification has come in an agreed upon narration wherein Allah’s Messenger -sallahu alayhi wa salaam- said, “5 practices are from the fitrah: circumcision, shaving the pubic hairs, trimming the mustache, plucking the underarms, and clipping the nails.” Muslim reported a narration (in his sahih) upon the authority of Anas ibn Malik wherein he said, “the appointed time limit for us to trim the mustache, clip the nails, pluck the underarms, and shave the pubic hairs, was that 40 days should not be abandoned without doing so.” And the woman is included in that which was mentioned just as the man.
Translated by Najeeb Al Anjelesi
Source: المنظار في بيان كثير من الأخطاء الشائعة