Language:
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 4164

Narrated Sa`id bin Al-Musaiyab:

That his father was amongst those who had given the Pledge of allegiance (to the Prophet (ﷺ) ) beneath the Tree, and the next year when they went towards the Tree, they were not able to recognize it.

حَدَّثَنَا مُوسَى، حَدَّثَنَا أَبُو عَوَانَةَ، حَدَّثَنَا طَارِقٌ، عَنْ سَعِيدِ بْنِ الْمُسَيَّبِ، عَنْ أَبِيهِ، أَنَّهُ كَانَ مِمَّنْ بَايَعَ تَحْتَ الشَّجَرَةِ، فَرَجَعْنَا إِلَيْهَا الْعَامَ الْمُقْبِلَ فَعَمِيَتْ عَلَيْنَا‏.‏
Reference : Sahih al-Bukhari 4164
In-book reference : Book 64, Hadith 206
USC-MSA web (English) reference : Vol. 5, Book 59, Hadith 482
  (deprecated numbering scheme)