Sahih al-Bukhari, Hadith 3955 ⓘ
Narrated Al-Bara: I and Ibn `Umar were considered too young to take part in the battle of Badr.
حَدَّثَنَا مُسْلِمٌ، حَدَّثَنَا شُعْبَةُ، عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، قَالَ اسْتُصْغِرْتُ أَنَا وَابْنُ، عُمَرَ.
also referenced under: Book 64, Hadith 7 (In-Book) & Volume 5, Book 59, Hadith 291 (USC-MSA)