Sahih al-Bukhari 1726
Sahih al-Bukhari · Book 25: Hajj (Pilgrimage) · To shave the head and to have the head-hair cut short on finishing the Ihram
Narrated Ibn `Umar:
حَدَّثَنَا أَبُو الْيَمَانِ ، أَخْبَرَنَا شُعَيْبُ بْنُ أَبِي حَمْزَةَ ، قَالَ نَافِعٌ كَانَ ابْنُ عُمَرَ ـ رضى الله عنهما ـ يَقُولُ حَلَقَ رَسُولُ اللَّهِ صلى الله عليه وسلم فِي حَجَّتِهِ.
Allah's Messenger (ﷺ) (p.b.u.h) (got) his head shaved after performing his Hajj.