Sunan Ibn Majah, Volume 4, Book 25, Hadith 3051 (DarusSalam) ⓘ
It was narrated from ‘Abdullah bin ‘Amr that the Prophet was asked about a man who slaughtered his sacrifice before shaving his head, or who shaved his head before slaughtering his sacrifice, and he said: “There is no harm in that.”
حَدَّثَنَا عَلِيُّ بْنُ مُحَمَّدٍ، حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، عَنِ الزُّهْرِيِّ، عَنْ عِيسَى بْنِ طَلْحَةَ، عَنْ عَبْدِ اللَّهِ بْنِ عَمْرٍو، أَنَّ النَّبِيَّ ـ صلى الله عليه وسلم ـ سُئِلَ عَمَّنْ ذَبَحَ قَبْلَ أَنْ يَحْلِقَ أَوْ حَلَقَ قَبْلَ أَنْ يَذْبَحَ قَالَ " لاَ حَرَجَ " .
also referenced under: Hadith 3051 (Reference) & Book 25, Hadith 3167 (In-Book)