Sahih al-Bukhari 5966
Narrated Aiyub:
The worst of three (persons riding one, animal) was mentioned in `Ikrima's presence `Ikrima said, 
"Ibn `Abbas said, '(In the year of the conquest of Mecca) the Prophet (ﷺ) came and mounted Qutham 
in front of him and Al-Fadl behind him, or Qutham behind him and Al-Fadl in front of him.' Now 
which of them was the worst off and which was the best?"
حَدَّثَنِي مُحَمَّدُ بْنُ بَشَّارٍ، حَدَّثَنَا عَبْدُ الْوَهَّابِ، حَدَّثَنَا أَيُّوبُ، ذُكِرَ الأَشَرُّ الثَّلاَثَةُ عِنْدَ عِكْرِمَةَ فَقَالَ قَالَ ابْنُ عَبَّاسٍ أَتَى رَسُولُ اللَّهِ صلى الله عليه وسلم وَقَدْ حَمَلَ قُثَمَ بَيْنَ يَدَيْهِ، وَالْفَضْلَ خَلْفَهُ، أَوْ قُثَمَ خَلْفَهُ، وَالْفَضْلَ بَيْنَ يَدَيْهِ، فَأَيُّهُمْ شَرٌّ أَوْ أَيُّهُمْ خَيْرٌ‏.‏