Sahih Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Volume: 005 / Book Number: 059 / Hadith Number: 488
Narrated Al-Musaiyab:
I met Al-Bara bin 'Azib and said (to him). "May you live prosperously! You enjoyed the company of the Prophet and gave him the Pledge of allegiance (of Al-Hudaibiya) under the Tree." On that, Al-Bara' said, "O my nephew! You do not know what we have done after him (i.e. his death)."