كتاب فضائل الصحابة رضى الله تعالى عنهم
44  
The Book of the Merits of the Companions
(8)
Chapter: The Virtues Of Al-Hasan And Al-Husain (RA)
(8)
باب فَضَائِلِ الْحَسَنِ وَالْحُسَيْنِ رضى الله عنهما ‏‏
Sahih Muslim 2423

Iyas reported on the authority of his father:

I (had the honour of) leading the white mule on which rode Allah's Apostle (ﷺ) and with him were Hasan and Husain, till it reached the apartment of Allah's Apostle (ﷺ). The one amongst them was seated before him and the other one was seated behind him.
حَدَّثَنِي عَبْدُ اللَّهِ بْنُ الرُّومِيِّ الْيَمَامِيُّ، وَعَبَّاسُ بْنُ عَبْدِ الْعَظِيمِ الْعَنْبَرِيُّ، قَالاَ حَدَّثَنَا النَّضْرُ بْنُ مُحَمَّدٍ، حَدَّثَنَا عِكْرِمَةُ، - وَهُوَ ابْنُ عَمَّارٍ - حَدَّثَنَا إِيَاسٌ، عَنْ أَبِيهِ، قَالَ لَقَدْ قُدْتُ بِنَبِيِّ اللَّهِ صلى الله عليه وسلم وَالْحَسَنِ وَالْحُسَيْنِ بَغْلَتَهُ الشَّهْبَاءَ حَتَّى أَدْخَلْتُهُمْ حُجْرَةَ النَّبِيِّ صلى الله عليه وسلم هَذَا قُدَّامَهُ وَهَذَا خَلْفَهُ ‏.‏
Reference : Sahih Muslim 2423
In-book reference : Book 44, Hadith 90
USC-MSA web (English) reference : Book 31, Hadith 5954
  (deprecated numbering scheme)