أَخْبَرَنَا يَعْقُوبُ بْنُ إِبْرَاهِيمَ، قَالَ حَدَّثَنَا هُشَيْمٌ، قَالَ أَنْبَأَنَا مَنْصُورٌ، عَنِ ابْنِ سِيرِينَ، قَالَ مُرَّ بِجَنَازَةٍ عَلَى الْحَسَنِ بْنِ عَلِيٍّ وَابْنِ عَبَّاسٍ فَقَامَ الْحَسَنُ وَلَمْ يَقُمِ ابْنُ عَبَّاسٍ فَقَالَ الْحَسَنُ لاِبْنِ عَبَّاسٍ أَمَا قَامَ لَهَا رَسُولُ اللَّهِ صلى الله عليه وسلم قَالَ ابْنُ عَبَّاسٍ قَامَ لَهَا ثُمَّ قَعَدَ .
It was narrated that Ibn Sirin said: "A funeral passed by Al-Hasan bin 'Ali and Ibn 'Abbas. Al-Hasan stood up but Ibn 'Abbas did not. Al-Hasan said to Ibn 'Abbas: 'Didn't the Messengr of Allah stand up for it?' Ibn 'Abbas said: 'He stood up for it then he sat."' Translation Not Available
Book Ref: Sunan An Nisai Book 21 Hadith 1925
Web Ref: Sunan An Nisai Vol 3 Book 21 Hadith 1926