Sahih al-Bukhari 7110
Narrated Harmala:
(Usama's Maula) Usama (bin Zaid) sent me to `Ali (at Kufa) and said, "`Ali will ask you, 'What has 
prevented your companion from joining me?' You then should say to him, 'If you (`Ali) were in the 
mouth of a lion, I would like to be with you, but in this matter I won't take any part.' " Harmala added: 
"`Ali didn't give me anything (when I conveyed the message to him) so I went to Hasan, Hussain and 
Ibn Ja`far and they loaded my camels with much (wealth).
حَدَّثَنَا عَلِيُّ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُفْيَانُ، قَالَ قَالَ عَمْرٌو أَخْبَرَنِي مُحَمَّدُ بْنُ عَلِيٍّ، أَنَّ حَرْمَلَةَ، مَوْلَى أُسَامَةَ أَخْبَرَهُ قَالَ عَمْرٌو وَقَدْ رَأَيْتُ حَرْمَلَةَ قَالَ أَرْسَلَنِي أُسَامَةُ إِلَى عَلِيٍّ وَقَالَ إِنَّهُ سَيَسْأَلُكَ الآنَ فَيَقُولُ مَا خَلَّفَ صَاحِبَكَ فَقُلْ لَهُ يَقُولُ لَكَ لَوْ كُنْتَ فِي شِدْقِ الأَسَدِ لأَحْبَبْتُ أَنْ أَكُونَ مَعَكَ فِيهِ، وَلَكِنَّ هَذَا أَمْرٌ لَمْ أَرَهُ، فَلَمْ يُعْطِنِي شَيْئًا، فَذَهَبْتُ إِلَى حَسَنٍ وَحُسَيْنٍ وَابْنِ جَعْفَرٍ فَأَوْقَرُوا لِي رَاحِلَتِي‏.‏