Question:

Last year I cut my hair on the 5th day of Dhul Hijja and then I came to know that we should not cut our hair if we intend to do Qurbānī. So was my qurbānī accepted or not?

Answer:

In the Name of Allah, the Most Gracious, the Most Merciful.
As-salāmu ‘alaykum wa-rahmatullāhi wa-barakātuh.
It is desirable for the one who will be sacrificing an animal for qurbānī to avoid cutting their hair or nails until after the animal is slaughtered. Rasulullah salallahu alayhi wasallam said:
“When the ten days (of Dhul Hijjah) begin and a person has an animal for sacrifice which he intends to slaughter, then let him not cut his hair or trim his nails.” (Muslim)
Rasulullah salallahu alayhi wasallam said in another Hadith:
“Whoever has an animal for slaughtering, once the crescent of Dhul Hijjah has been declared he should not cut his hair or trim his nails until he has sacrificed (the animal)” (Muslim)
It is a recommended act due to the Hadīth. However, if one did cut his hair and/or nails during the first ten days of Dhul Hijjah before sacrificing, it will not affect the validity of making qurbānī.

قال رسول الله صلى الله عليه و سلم: دخل العشر و عنده اضحية يريد ان يضحى, فلا ياخذن شعرا ولا يقلمن ظفرا
(Saīih Muslim, 2/160, Qadīmi Kutub Khāna)

وحدثنى عبيد الله بن معاذ العنبرى حدثنا أبى حدثنا محمد بن عمرو الليثى عن عمر بن مسلم بن عمار بن أكيمة الليثى قال سمعت سعيد بن المسيب يقول سمعت أم سلمة زوج النبى -صلى الله عليه وسلم- تقول قال رسول الله -صلى الله عليه وسلم- « من كان له ذبح يذبحه فإذا أهل هلال ذى الحجة فلا يأخذن من شعره ولا من أظفاره شيئا حتى يضحى
(Sahiī Muslim #5236)

ومما ورد في صحيح مسلم قال رسول الله (ص): إذا دخل العشر وأراد بعضكم أن يضحي فلا يأخذن شعرا ولا يقلمن ظفرا فهذا محمول على الندب دون الوجوب بالاجماع
(Raddul Muhtār, 2/181, H.M Sa῾īd)
(Fatāwa Mahmūdiyah, 17/486, Farūqiyyah)
And Allah Ta’āla Knows Best
Checked and Approved by,
Mufti Ebrahim Desai.