Language:
كتاب الأذان
10  
Call to Prayers (Adhaan)
(161)
Chapter: The ablution for boys (youngsters). When they should perform Ghusl (take a bath) and Tuhur (purification). Their attendance at congregational prayers and their rows in the prayers.
(161)
باب وُضُوءِ الصِّبْيَانِ
Sahih al-Bukhari 857

Narrated Sulaiman Ash-Shaibani:

I heard Ash-Shu`bi saying, "A person who was accompanying the Prophet (ﷺ) passed by a grave that was separated from the other graves told me that the Prophet (ﷺ) once led the people in the (funeral) prayer and the people had aligned behind him. I said, "O Aba `Amr! Who told you about it?" He said, "Ibn `Abbas."

حَدَّثَنَا ابْنُ الْمُثَنَّى، قَالَ حَدَّثَنِي غُنْدَرٌ، قَالَ حَدَّثَنَا شُعْبَةُ، قَالَ سَمِعْتُ سُلَيْمَانَ الشَّيْبَانِيَّ، قَالَ سَمِعْتُ الشَّعْبِيَّ، قَالَ أَخْبَرَنِي مَنْ، مَرَّ مَعَ النَّبِيِّ صلى الله عليه وسلم عَلَى قَبْرٍ مَنْبُوذٍ، فَأَمَّهُمْ وَصَفُّوا عَلَيْهِ‏.‏ فَقُلْتُ يَا أَبَا عَمْرٍو مَنْ حَدَّثَكَ فَقَالَ ابْنُ عَبَّاسٍ‏.‏
Reference : Sahih al-Bukhari 857
In-book reference : Book 10, Hadith 248
USC-MSA web (English) reference : Vol. 1, Book 12, Hadith 816
  (deprecated numbering scheme)