أَخْبَرَنَا مُحَمَّدُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ مُطَرِّفِ بْنِ طَرِيفٍ، عَنِ الشَّعْبِيِّ، قَالَ سَمِعْتُ أَبَا جُحَيْفَةَ، يَقُولُ سَأَلْنَا عَلِيًّا فَقُلْنَا هَلْ عِنْدَكُمْ مِنْ رَسُولِ اللَّهِ صلى الله عليه وسلم شَىْءٌ سِوَى الْقُرْآنِ فَقَالَ لاَ وَالَّذِي فَلَقَ الْحَبَّةَ وَبَرَأَ النَّسَمَةَ إِلاَّ أَنْ يُعْطِيَ اللَّهُ عَزَّ وَجَلَّ عَبْدًا فَهْمًا فِي كِتَابِهِ أَوْ مَا فِي هَذِهِ الصَّحِيفَةِ ‏.‏ قُلْتُ وَمَا فِي الصَّحِيفَةِ قَالَ فِيهَا ‏"‏ الْعَقْلُ وَفِكَاكُ الأَسِيرِ وَأَنْ لاَ يُقْتَلَ مُسْلِمٌ بِكَافِرٍ ‏"‏ ‏.‏

It was narrated that Ash-Sha'bi said: "I heard Abu Juhaifah say: 'We asked 'Ali: "Do you have anything from the Messenger of Allah apart from the Qur'an?" He said: "No, by the One who splits the seeds and creates the soul, unless Allah gives a slave understanding of His Book, or except this sheet." I said: "What is in the sheet?" He said: "In it are (the regulations concerning) blood money and the freeing of captives and (the rule) that no Muslim should be killed for killing a disbeliever." Translation Not Available

Book reference: Sunan An Nisai Book 45 Hadith 4744
Web reference: Sunan An Nisai Volume 5 Book 45 Hadith 4748