Language:
كتاب الحج
25  
Hajj (Pilgrimage)
(125)
Chapter: Slaughtering before having one’s head shaved
(125)
باب الذَّبْحِ قَبْلَ الْحَلْقِ
Sahih al-Bukhari 1724

Narrated Abu Musa:

I came upon Allah's Messenger (ﷺ) when he was at Al-Batha. He asked me, "Have you intended to perform the Hajj?" I replied in the affirmative. He asked, "For what have you assumed lhram?" I replied," I have assumed Ihram with the same intention as that of the Prophet (ﷺ) ." The Prophet (ﷺ) said, "You have done well! Go and perform Tawaf round the Ka`ba and between Safa and Marwa." Then I went to one of the women of Bani Qais and she took out lice from my head. Later, I assumed the Ihram for Hajj. So, I used to give this verdict to the people till the caliphate of `Umar. When I told him about it, he said, "If we take (follow) the Holy Book, then it orders us to complete Hajj and `Umra (Hajj-at- Tamattu`) and if we follow the tradition of Allah's Messenger (ﷺ) then Allah's Messenger (ﷺ) did not finish his lhram till the Hadi had reached its destination (had been slaughtered). (i.e. Hajj-al-Qiran). (See Hadith No. 630)

حَدَّثَنَا عَبْدَانُ، قَالَ أَخْبَرَنِي أَبِي، عَنْ شُعْبَةَ، عَنْ قَيْسِ بْنِ مُسْلِمٍ، عَنْ طَارِقِ بْنِ شِهَابٍ، عَنْ أَبِي مُوسَى ـ رضى الله عنه ـ قَالَ قَدِمْتُ عَلَى رَسُولِ اللَّهِ صلى الله عليه وسلم وَهُوَ بِالْبَطْحَاءِ‏.‏ فَقَالَ ‏"‏ أَحَجَجْتَ ‏"‏‏.‏ قُلْتُ نَعَمْ‏.‏ قَالَ ‏"‏ بِمَا أَهْلَلْتَ ‏"‏‏.‏ قُلْتُ لَبَّيْكَ بِإِهْلاَلٍ كَإِهْلاَلِ النَّبِيِّ صلى الله عليه وسلم‏.‏ قَالَ ‏"‏ أَحْسَنْتَ، انْطَلِقْ فَطُفْ بِالْبَيْتِ وَبِالصَّفَا وَالْمَرْوَةِ ‏"‏‏.‏ ثُمَّ أَتَيْتُ امْرَأَةً مِنْ نِسَاءِ بَنِي قَيْسٍ، فَفَلَتْ رَأْسِي، ثُمَّ أَهْلَلْتُ بِالْحَجِّ، فَكُنْتُ أُفْتِي بِهِ النَّاسَ، حَتَّى خِلاَفَةِ عُمَرَ ـ رضى الله عنه ـ فَذَكَرْتُهُ لَهُ‏.‏ فَقَالَ إِنْ نَأْخُذْ بِكِتَابِ اللَّهِ فَإِنَّهُ يَأْمُرُنَا بِالتَّمَامِ، وَإِنْ نَأْخُذْ بِسُنَّةِ رَسُولِ اللَّهِ صلى الله عليه وسلم فَإِنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم لَمْ يَحِلَّ حَتَّى بَلَغَ الْهَدْىُ مَحِلَّهُ‏.‏
Reference : Sahih al-Bukhari 1724
In-book reference : Book 25, Hadith 202
USC-MSA web (English) reference : Vol. 2, Book 26, Hadith 782
  (deprecated numbering scheme)