Hadith 8
“How will you judge if a case is brought to you?”
Mu’ath replied “I would judge by the Book of Allah” to which the Prophet asked “And if you do not find (an answer) in the book of Allah?”
Mu’ath said “Then by the sunnah of the Messenger of Allah”. The Prophet then asked “and if you do not find (an answer) in the Sunnah or the Book of Allah” to which Mu’ath replied he would exert his own opinion (meaning ijtihaad based upon the Qur’an and Sunnah)
كَيْفَ تَقْضِي قَالَ أَقْضِي بِكِتَابِ اللَّهِ قَالَ فَإِنْ لَمْ يَكُنْ فِي كِتَابِ اللَّهِ قَالَ فَبِسُنَّةِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ فَإِنْ لَمْ يَكُنْ فِي سُنَّةِ رَسُولِ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ أَجْتَهِدُ رَأْيِي
(Abu Dawud/ Ahmed)
Commentary
a. Confirmation that the two principle sources of guidance and legislation for Muslims is the Quran and the authentic sunnah.
b. If there is no clear direct text in the Quran and Sunnah for a specific issue – then the process of ijtihaad is for a scholar/ judge to exert the utmost effort to find the hukm shari’ (rule of the Shari’ah) for what is confronting them.
c. The four agreed usool (basis) for rules according to the ahlul Sunnah are Quran, Sunnah, Ijma’a (consensus) and Qiyas (analogy/ reasoning)
Taken from the book “The Sixty Sultaniyya”