Dhul-Hijjah

It is forbidden for someone who wants to make a sacrifice to remove anything from their hair or nails

during the first 10 days of Dhul-Hijjah.

Umm Salama reported Allah’s Messenger ﷺ as saying,

“If anyone sees the new moon of Dhul Hijja and intends to sacrifice, he must not take any of its hairs or nails.”

Mishkat al-Masabih 1459