Sahih al-Bukhari 4175
Sahih al-Bukhari · Book 64: Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi) · The Ghazwa of Al-Hudaibiya
Narrated Suwaid bin An-Nu`man:
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 .
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.