Short answer
It is better not to. In the Hanafi school it is mustahabb for someone giving qurbani not to cut hair or nails from 1 Dhul Hijjah until the sacrifice is done, but it is not a sin to cut them. The Hanbali school holds it is haram, and the Shafi'i school makruh.
For a person intending qurbani, leaving hair and nails uncut from the first of Dhul Hijjah until his animal is slaughtered is mustahabb. Cutting them is not sinful and does not affect the qurbani. If it has been close to forty days since the last trim, he should trim, since going beyond forty days is disliked.
Other madhhabs
- Shafi'i
- Cutting them is makruh tanzihi for the one intending to sacrifice.
- Hanbali
- Cutting them is haram for the one intending to sacrifice, though the qurbani is still valid and he should seek forgiveness.
- Maliki
- Cutting them is makruh in this period for the one intending to sacrifice.
Explanation
The Prophet ﷺ said that when the ten days begin and one of you intends to sacrifice, he should not touch any of his hair or skin. Scholars mention that the one sacrificing resembles the pilgrims in ihram in a small way. The Hanafi school reads it as a recommendation, partly because A'ishah reported that the Prophet sent his sacrificial animals to Makkah while nothing became forbidden for him at home.
- Who it applies to: the person whose qurbani it is. Family members whose reward is shared, or who are not sacrificing, are not addressed by the hadith.
- When it starts: at sunset on the last day of Dhul Qa'dah, when the new month begins.
- When it ends: when your animal is slaughtered, even if that is on the second or third day of Eid. If someone else does it for you abroad, wait until you know it is done.
- What it covers: head hair, moustache, armpit and pubic hair, and nails.
- Not sacrificing: some Hanafi scholars encourage refraining anyway, hoping for a share of the reward.
Cutting by mistake or out of need, such as a broken nail, carries no penalty. For the other virtues of these days, see the first 10 days of Dhul Hijjah.
The evidence
Sahih Muslim 1977
Sahih... إذا دخلت العشر وأراد أحدكم أن يضحي فلا يمس ...
"When the ten days begin and one of you intends to sacrifice, let him not touch any of his hair or skin."
The basis of refraining from cutting hair and nails.
Where the ruling is recorded
- Radd al-Muhtar (Ibn Abidin), Kitab al-Udhiyah. Refraining is mustahabb, not wajib.
- Kashshaf al-Qina', Kitab al-Hajj, bab al-hadi wal-adahi. The Hanbali view that it is forbidden for the one sacrificing.
- al-Majmu' (Nawawi), Kitab al-Udhiyah. The Shafi'i view of makruh.
This answer is pending review by the scholars on our team. Quran translation by Sahih International. Hadith Arabic from the standard editions of the six books and the Muwatta, with gradings as recorded there; the English is our own rendering. Spotted a mistake? Tell us.