حَدَّثَنِي مَحْمُودٌ، حَدَّثَنَا وَهْبٌ، عَنْ شُعْبَةَ، عَنْ أَبِي إِسْحَاقَ، عَنِ الْبَرَاءِ، قَالَ اسْتُصْغِرْتُ أَنَا وَابْنُ عُمَرَ يَوْمَ بَدْرٍ، وَكَانَ الْمُهَاجِرُونَ يَوْمَ بَدْرٍ نَيِّفًا عَلَى سِتِّينَ، وَالأَنْصَارُ نَيِّفًا وَأَرْبَعِينَ وَمِائَتَيْنِ‏.‏

Narrated 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. Translation Not Available

Book Ref: Sahih Bukhari Book 64 Hadith 3956
Web Ref:  Sahih Bukhari Vol 5 Book 59 Hadith 292