4-Surah An-Nisa ( The Women ) 65
But no, by your Lord, they will not [truly] believe until they make you, [O Muhammad], judge concerning that over which they dispute among themselves and then find within themselves no discomfort from what you have judged and submit in [full, willing] submission.
فَلَا وَرَبِّكَ لَا يُؤْمِنُونَ حَتَّىٰ يُحَكِّمُوكَ فِيمَا شَجَرَ بَيْنَهُمْ ثُمَّ لَا يَجِدُوا فِي أَنفُسِهِمْ حَرَجًا مِّمَّا قَضَيْتَ وَيُسَلِّمُوا تَسْلِيمًا
Quran's Tafhim ( explanation)
*95).The application of the injunction embodied in this verse is not confined to the life-time of the Prophet (peace be on him). It will remain in force until the Day of Judgement. The guidance the Prophet (peace be on him) proclaimed on God's behalf, and the manner in which he followed God's direction and inspiration, will for ever remain the universal touchstone for Muslims. In fact, recognition of that guidance as the final authority is the criterion of true belief. This principle was pronounced by the Prophet (peace be on him) in the following words: 'None of you can become a believer until his desires become subservient to what I have brought (i.e. my teachings).' (Cited by al-Nawawi in al-Arba'in, see the tradition no. 41, transmitted on their authority of Abu al-Qasim Isma'il b. Muhammad al-Isfahani, Kitab al-Hujjah with the opinion that it is a 'good' and 'sound' tradition, with a sound chain of transmission - Ed.)