﴿ يَٰٓأَيُّهَا ٱلَّذِينَ ءَامَنُوٓا۟ أَطِيعُوا۟ ٱللَّهَ وَأَطِيعُوا۟ ٱلرَّسُولَ وَأُو۟لِى ٱلْأَمْرِ مِنكُمْ ۖ فَإِن تَنَٰزَعْتُمْ فِى شَىْءٍۢ فَرُدُّوهُ إِلَى ٱللَّهِ وَٱلرَّسُولِ إِن كُنتُمْ تُؤْمِنُونَ بِٱللَّهِ وَٱلْيَوْمِ ٱلْءَاخِرِ ۚ ذَٰلِكَ خَيْرٌۭ وَأَحْسَنُ تَأْوِيلًا ﴾

“O you who have attained to faith! Pay heed unto God, and pay heed unto the Apostle and unto those from among you who have been entrusted with authority; and if you are at variance over any matter, refer it unto God and the Apostle, if you [truly] believe in God and the Last Day. This is the best [for you], and best in the end.”

The Proof of Ijtihad اِجتِھاد and Qiyas قیاس Finally, let us now refer to the statement: فَإِن تَنَازَعْتُمْ فِي شَيْءٍ فَرُ‌دُّوهُ إِلَى اللَّـهِ وَالرَّ‌سُولِ in verse 59 (Then, if you quarrel about something, revert it back to Allah and the Messenger.) This 'reverting back to Allah and the Messenger' takes two forms: 1. Revert to ahkam, the code of commands as mandated in the Book of Allah and the Sunnah of the Messenger of Allah. 2. If the textually-mandated ahkam do not exist, the act of reverting back will be accomplished by analogical deduction (Qiyas) as based on their precedents. The words of the expression: فَرُدُّہ (revert it back) are general, thus being inclusive of both forms.