Sahih Bukhari
Sahih Bukhari Volume 005, Book 059, Hadith Number 292.
Hadith Section/Book: Sahih Bukhari Sahih Bukhari Book 59. Military Expeditions Led by the Prophet (PBUH) (Al-Maghaazi)
Narrated By Al-Bara: I and Ibn 'Umar were considered too young (to take part) in the battle of Badr, and the number of the Emigrant warriors were over sixty (men) and the Ansar were over 249.