A Woman Is Allowed To Trim Her Hair
Question to Shaikh Al-Albānī (no. 1): What is the ruling for a woman wishing to trim from the length of her hair?
Answer: A reason behind a woman trimming her hair should be considered. So if a woman trims her hair seeking to imitate the unbelieving or the wicked and sinful women, then it is not permitted with that intention.
However, if she takes just a small amount from [the length of] her hair or in fulfilling the wants of her husband, then I see no problem in that.
There occurs in the hadeeth reported in Saheeh Muslim (no. 320) that the wives of the Prophet (salallāhu ‘alaihi wasallam) would trim their hair until it would become copious and ample.
(Masā’il wa Ajwibatuhā lil-‘Allāmah Al-Muhaddith Nāsirud-Deen Al-Albānī, p. 7)