Narrated Ash-Shaibani:

Ash-Sha'bi said, "Somebody who passed along with your Prophet ﷺ by a grave that was separate from the other graves informed me (saying), "The Prophet 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 ﷺ عَلَى قَبْرٍ مَنْبُوذٍ فَأَمَّنَا فَصَفَفْنَا خَلْفَهُ. فَقُلْنَا يَا أَبَا عَمْرٍو مَنْ حَدَّثَكَ قَالَ ابْنُ عَبَّاسٍ رضى الله عنهما.