Language:
كتاب الجهاد والسير
56  
Fighting for the Cause of Allah (Jihaad)
(126)
Chapter: The sitting of two men together over a riding animal
(126)
باب الاِرْتِدَافِ فِي الْغَزْوِ وَالْحَجِّ
Sahih al-Bukhari 2986

Narrated Anas:

I was riding behind Abu Talha (on the same) riding animal and (the Prophet's companions) were reciting Talbiya aloud for both Hajj and `Umra.

حَدَّثَنَا قُتَيْبَةُ بْنُ سَعِيدٍ، حَدَّثَنَا عَبْدُ الْوَهَّابِ، حَدَّثَنَا أَيُّوبُ، عَنْ أَبِي قِلاَبَةَ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ كُنْتُ رَدِيفَ أَبِي طَلْحَةَ، وَإِنَّهُمْ لَيَصْرُخُونَ بِهِمَا جَمِيعًا الْحَجِّ وَالْعُمْرَةِ‏.‏
Reference : Sahih al-Bukhari 2986
In-book reference : Book 56, Hadith 195
USC-MSA web (English) reference : Vol. 4, Book 52, Hadith 229
  (deprecated numbering scheme)