(125) باب الذَّبْحِ قَبْلَ الْحَلْقِ
Narrated Ibn `Abbas:
The Prophet (ﷺ) was asked about a person who had his head shaved before slaughtering (his Hadi) (or other similar ceremonies of Hajj). He replied, "There is no harm, there is no harm."
Reference: Sahih al-Bukhari 1721
In-book reference: Book 25, Hadith 199
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 2, Book 26, Hadith 779