Sahih Bukhari
Merits of the Helpers in Madinah (Ansaar)
Volume: 005 / Book Number: 058 / Hadith Number: 230
Narrated Jabir bin 'Abdullah:
I was present with my two maternal uncles at Al-'Aqaba (where the pledge of allegiance was given). (Ibn 'Uyaina said, "One of the two was Al-Bara' bin Marur.")