Answered by Ustadh Salman Younas
Question: Should one not cut his hair or trim his nails from the 1st of Dhu’l Hijja if intending to sacrifice? What is the evidence for this?Answer: assaalmu `alaykum
It would be recommended not to cut your hair or trim your nails if you intend to sacrifice. Please refer to the following: Cutting Hair and Nails Before Slaughtering on Eid
The evidence for this is the narration of Umm Salama that the Prophet (Allah bless him) said, “Whoever sights the crescent of the moon of Dhu’l Hijja and intends to sacrifice an animal should neither cut his hair or nails.” [Muslim, Abu Dawud, Tirmidhi]
This is understood to be a recommendation based on the fact that `A’isha relates that the Prophet (Allah bless him) sent a sacrificial animal to be slaughtered during the Hajj seasons while in Madina but he did not abstain from those things that a person performing Hajj abstains from. [Bukhari, Muslim] As such, this action indicates that the instruction of the Prophet (Allah bless him) mentioned in the first narration was not for obligation but recommendation.
Checked & Approved by Shaykh Faraz Rabbani.