Pilgrims Prevented from Completing the Pilgrimage
حَدَّثَنَا مَحْمُودٌ، حَدَّثَنَا عَبْدُ الرَّزَّاقِ، أَخْبَرَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ عُرْوَةَ، عَنِ الْمِسْوَرِ ـ رضى الله عنه ـ أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم نَحَرَ قَبْلَ أَنْ يَحْلِقَ، وَأَمَرَ أَصْحَابَهُ بِذَلِكَ.Narrated Al-Miswar:Allah's Messenger (ﷺ) slaughtered (the Hadi) before he had his head shaved and then he ordered his Companions to do the same
From Sahih al-Bukhari, whose reports the scholars accept as authentic.