Sahih Bukhari Volume 004, Book 056, Hadith Number 695.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 56. Virtues and Merits of the Prophets (PBUH) and his Companions
Narated By Ibn Abbas : Regarding the Verse: 'And (We) made you into Shu'ub and Qabail... (49.13) that Shu'uib means the big Qabail (i.e. nations) while the Qabail (i.e. tribes) means the branch tribes.