Narrated Ash-Shaibani:

Ash Shu`bi said, "I was informed by a man who had seen the Prophet (ﷺ) going to a grave that was separate from the other graves and he aligned the people in rows and said four Takbir." I said, "O Abu `Amr! who narrated (that) to you"? He said, "Ibn `Abbas. "

حَدَّثَنَا مُسْلِمٌ، حَدَّثَنَا شُعْبَةُ، حَدَّثَنَا الشَّيْبَانِيُّ، عَنِ الشَّعْبِيِّ، قَالَ أَخْبَرَنِي مَنْ، شَهِدَ النَّبِيَّ صلى الله عليه وسلم أَنَّهُ أَتَى عَلَى قَبْرٍ مَنْبُوذٍ فَصَفَّهُمْ وَكَبَّرَ أَرْبَعًا‏.‏ قُلْتُ مَنْ حَدَّثَكَ قَالَ ابْنُ عَبَّاسٍ رضى الله عنهما‏.‏