Sahih al-Bukhari 77
Sahih al-Bukhari · Book 3: Knowledge · At what age may a youth be listened to (i.e. quotation of the Hadith from a boy be acceptable)
Narrated Mahmud bin Rabi`a:
حَدَّثَنِي مُحَمَّدُ بْنُ يُوسُفَ ، قَالَ حَدَّثَنَا أَبُو مُسْهِرٍ ، قَالَ حَدَّثَنِي مُحَمَّدُ بْنُ حَرْبٍ ، حَدَّثَنِي الزُّبَيْدِيُّ ، عَنِ الزُّهْرِيِّ ، عَنْ مَحْمُودِ بْنِ الرَّبِيعِ ، قَالَ عَقَلْتُ مِنَ النَّبِيِّ صلى الله عليه وسلم مَجَّةً مَجَّهَا فِي وَجْهِي وَأَنَا ابْنُ خَمْسِ سِنِينَ مِنْ دَلْوٍ.
When I was a boy of five, I remember, the Prophet (ﷺ) took water from a bucket (used for getting water out of a well) with his mouth and threw it on my face.