The Hadith in question has been mentioned by Imam Muslim Rahmatullahi Alaihi in his Sunan under the chapter,” It is not permissible for one who intends to sacrifice the animal to get one’s hair or nails cut after the beginning of Zul Hijjah”
The Fuqaha have deduced from this Hadith that it is Mustahab (preferable, meritorious) for any person who intends to sacrifice
an animal for Qurbani to avoid cutting their hair and clipping their nails until the animal has been slaughtered.
However, if someone cuts his nails or hair they will not be sinful.
