Sahih al-Bukhari 1811

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

Reference

Sahih al-Bukhari 1811

In-book

Book 27, Hadith 6

English

Muhsin Khan