Language:
كتاب الذبائح والصيد
72  
Hunting, Slaughtering
(35)
Chapter: Branding the faces
(35)
باب الْوَسْمِ وَالْعَلَمِ فِي الصُّورَةِ
Sahih al-Bukhari 5542

Narrated Anas:

I brought a brother of mine to the Prophet (ﷺ) to do Tahnik for him while the Prophet (ﷺ) was in a sheep fold of his, and I saw him branding a sheep. (The sub-narrator said: I think Anas said, branding it on the ear.)

حَدَّثَنَا أَبُو الْوَلِيدِ، حَدَّثَنَا شُعْبَةُ، عَنْ هِشَامِ بْنِ زَيْدٍ، عَنْ أَنَسٍ، قَالَ دَخَلْتُ عَلَى النَّبِيِّ صلى الله عليه وسلم بِأَخٍ لِي يُحَنِّكُهُ، وَهْوَ فِي مِرْبَدٍ لَهُ، فَرَأَيْتُهُ يَسِمُ شَاةً ـ حَسِبْتُهُ قَالَ ـ فِي آذَانِهَا‏.‏
Reference : Sahih al-Bukhari 5542
In-book reference : Book 72, Hadith 67
USC-MSA web (English) reference : Vol. 7, Book 67, Hadith 450
  (deprecated numbering scheme)