Hadith #197
English (English)When you see the crescent of Dhul Hijjah and one of you intends to make sacrifice, he must not shave (trim) his hair or clip his nails.
Reference: صحیح مسلم، كتاب الأضاحي، باب نهي من دخل عليه عشر ذي الحجة۔۔۔إلخ، الحدیث 1977