كتاب المغازى
64  
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
(35)
Chapter: The Ghazwa of Al-Hudaibiya
(35)
باب غَزْوَةِ الْحُدَيْبِيَةِ
Sahih al-Bukhari 4175

Narrated Suwaid bin An-Nu`man:

who was one of those who witnessed (the Pledge of allegiance beneath) the Tree: Allah's Messenger (ﷺ) and his companions were given Sawiq and they chewed it.

حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا ابْنُ أَبِي عَدِيٍّ، عَنْ شُعْبَةَ، عَنْ يَحْيَى بْنِ سَعِيدٍ، عَنْ بُشَيْرِ بْنِ يَسَارٍ، عَنْ سُوَيْدِ بْنِ النُّعْمَانِ ـ وَكَانَ مِنْ أَصْحَابِ الشَّجَرَةِ ـ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم وَأَصْحَابُهُ أُتُوا بِسَوِيقٍ فَلاَكُوهُ‏.‏ تَابَعَهُ مُعَاذٌ عَنْ شُعْبَةَ‏.‏
Reference : Sahih al-Bukhari 4175
In-book reference : Book 64, Hadith 217
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 492
  (deprecated numbering scheme)