(6) باب عِدَّةِ أَصْحَابِ بَدْرٍ
Narrated Al-Bara:
I and Ibn `Umar were considered too young to take part in the battle of Badr.
Reference: Sahih al-Bukhari 3955
In-book reference: Book 64, Hadith 7
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 5, Book 59, Hadith 291