Sahih al-Bukhari 857
Sahih al-Bukhari · Book 10: Call to Prayers (Adhaan) · 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.
Narrated Sulaiman Ash-Shaibani:
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 .
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."