Sahih al-Bukhari 1322
Narrated Ash-Shaibani:
Ash-Shu`bi said, "Somebody who passed along with your Prophet (p.b.u.h) by a grave that was 
separate from the other graves informed me (saying), "The Prophet (ﷺ) 
led us (in the prayer) and we aligned behind him." We said, "O Abu `Amr! Who told you this 
narration?" He replied, "Ibn `Abbas."
حَدَّثَنَا سُلَيْمَانُ بْنُ حَرْبٍ، حَدَّثَنَا شُعْبَةُ، عَنِ الشَّيْبَانِيِّ، عَنِ الشَّعْبِيِّ، قَالَ أَخْبَرَنِي مَنْ، مَرَّ مَعَ نَبِيِّكُمْ صلى الله عليه وسلم عَلَى قَبْرٍ مَنْبُوذٍ فَأَمَّنَا فَصَفَفْنَا خَلْفَهُ‏.‏ فَقُلْنَا يَا أَبَا عَمْرٍو مَنْ حَدَّثَكَ قَالَ ابْنُ عَبَّاسٍ رضى الله عنهما‏.‏