Sahih Bukhari Volume 4, Book 56, Hadith 3048

حَدَّثَنَا أَحْمَدُ بْنُ يُونُسَ، حَدَّثَنَا زُهَيْرٌ، حَدَّثَنَا مُطَرِّفٌ، أَنَّ عَامِرًا، حَدَّثَهُمْ عَنْ أَبِي جُحَيْفَةَ ـ رضى الله عنه ـ قَالَ قُلْتُ لِعَلِيٍّ ـ رضى الله عنه هَلْ عِنْدَكُمْ شَىْءٌ مِنَ الْوَحْىِ إِلاَّ مَا فِي كِتَابِ اللَّهِ قَالَ وَالَّذِي فَلَقَ الْحَبَّةَ وَبَرَأَ النَّسَمَةَ مَا أَعْلَمُهُ إِلاَّ فَهْمًا يُعْطِيهِ اللَّهُ رَجُلاً فِي الْقُرْآنِ، وَمَا فِي هَذِهِ الصَّحِيفَةِ‏.‏ قُلْتُ وَمَا فِي الصَّحِيفَةِ قَالَ الْعَقْلُ وَفَكَاكُ الأَسِيرِ، وَأَنْ لاَ يُقْتَلَ مُسْلِمٌ بِكَافِرٍ

Narrated By Abu Juhaifa : I asked Ali, "Do you have the knowledge of any Divine Inspiration besides what is in Allah's Book?" 'Ali replied, "No, by Him Who splits the grain of corn and creates the soul. I don't think we have such knowledge, but we have the ability of understanding which Allah may endow a person with, so that he may understand the Qur'an, and we have what is written in this paper as well." I asked, "What is written in this paper?" He replied, "(The regulations of) blood-money, the freeing of captives, and the judgment that no Muslim should be killed for killing an infidel."