Bismillah.
Volume 2, Book 26, Number 784:
Narrated Ibn 'Umar (radiallaahu `anhu):
Allah's Apostle (sallallaahu `alayhi wasallam) (got) his head shaved after performing his Hajj.
Volume 2, Book 26, Number 785:
Narrated Abdullah bin Umar (radiallaahu `anhu):
Allah's Apostle (sallallaahu `alayhi wasallam) said, "O Allah! Be merciful to those who have their head shaved." The people said, "O Allah's Apostle (sallallaahu `alayhi wasallam)! And (invoke Allah for) those who get their hair cut short." The Prophet (sallallaahu `alayhi wasallam) said, "O Allah! Be merciful to those who have their head shaved." The people said, "O Allah's Apostle (sallallaahu `alayhi wasallam)! And those who get their hair cut short." The Prophet (sallallaahu `alayhi wasallam) said (the third time), "And to those who get their hair cut short." Nafi' said that the Prophet (sallallaahu `alayhi wasallam) had said once or twice, "O Allah! Be merciful to those who get their head shaved," and on the fourth time he added, "And to those who have their hair cut short."
Volume 2, Book 26, Number 786:
Narrated Abu Huraira (radiallaahu `anhu):
Allah's Apostle (sallallaahu `alayhi wasallam) said, "O Allah! Forgive those who get their heads shaved." The people asked. "Also those who get their hair cut short?" The Prophet (sallallaahu `alayhi wasallam) said, "O Allah! Forgive those who have their heads shaved." The people said, "Also those who get their hair cut short?" The Prophet (sallallaahu `alayhi wasallam) (invoke Allah for those who have their heads shaved and) at the third time said, "also (forgive) those who get their hair cut short."
Volume 2, Book 26, Number 787:
Narrated 'Abdullah (radiallaahu `anhu):
The Prophet (sallallaahu `alayhi wasallam) and some of his companions got their heads shaved and some others got their hair cut short. Narrated Muawiya (radiallaahu `anhu): I cut short the hair of Allah's Apostle (sallallaahu `alayhi wasallam) with a long blade.
Volume 2, Book 26, Number 788:
Narrated Ibn Abbas (radiallaahu `anhu):
When the Prophet (sallallaahu `alayhi wasallam) came to Mecca, he ordered his Companions to perform Tawaf round the Ka'ba and between Safa and Marwa, to finish their Ihram and get their hair shaved off or cut short.
When the pilgrim who is doing Tamattu’ has completed seven circuits of saa’i, he should shave his head if he is a man, or cut his hair. If he shaves his head he must shave his entire head, and if he cuts his hair he must cut from all over his head. Shaving is better than cutting because the Prophet (peace and blessings of Allaah be upon him) made du’aa’ three times for those who shaved their heads and once for those who cut their hair. Narrated by Muslim, 1303.
But if the time of Hajj is so close that there will be no time for the hair to grow back, then it is better to cut one’s hair at this point, so that there will be some hair left to shave during Hajj. The evidence for that is the fact that the Prophet (peace and blessings of Allaah be upon him) commanded his companions, during the Farewell Pilgrimage, to cut their hair during ‘Umrah, because they arrived on the morning of the 4th of Dhu’l-Hijjah.
Women should cut the length of a fingertip from their hair.
