If a person cuts his hair after the month of Dhu’l-Hijjah has begun, and he intends to offer a sacrifice, is his sacrifice valid and will it be accepted?.
Shaykh Ibn ‘Uthaymeen said:
Yes, his sacrifice will be accepted but he will be a sinner. With regard to a widespread belief among the common people that if a man removes anything from his hair, nails or skin during the first ten days of Dhu’l-Hijjah, his sacrifice is not valid, this is not correct, because there is no connection between the validity of his sacrifice and his removing anything from these three things.
Al-Sharh al-Mumti’, 7/533
And Allaah knows best.