The ruling on shaving the Head or cutting the Hair for 'Umrah
Question :
What is the ruling on shaving the head or cutting the hair in reference to 'Umrah?
Answer:
Shaving the head or cutting the hair in reference to 'Umrah is obligatory. This is because when the Prophet came to Makkah during the Farewell Hajj, and he performed Tawaf and Say, he commanded everyone who had not brought a sacrificial animal to cut his hair and then shave his head (later for Hajj). Therefore, since he commanded them to cut their hair, and the basic principle regarding a command is that it is for obligation, this proves that the hair must be cut. What also alludes to this is that the Prophet commanded them, when they were prevented (from 'Umrah) during the expedition of Al- Hudaibiyyah, to shave their heads. This was such that the Prophet became angry when they were hesitant in doing so. In reference to whether it is better to cut the hair or shave the head for 'Umrah, it is better to shave the head except for the person performing Hajjut-Tamattu' and he has come to Makkah late. In that case, it is better for him to cut his hair so that he will have hair left for shaving his head for the Hajj.
Source:
Ash-Shaykh Ibn 'Uthaimin
Fatawa Islamiyah, Vol. 4 Page 212