[Machine] The Messenger of Allah ﷺ said, "I have not left anything that Allah has commanded you with, except that I have commanded you with it. And I have not left anything that Allah has forbidden you from, except that I have forbidden you from it." Imam Ash-Shafi'i (may Allah have mercy on him) said, "If there is no revelation in it, then Allah has made following His Sunnah obligatory in the revelation. So whoever accepts it, accepts the obligation of Allah. And Allah, the Most High, knows best."  

أَنَّ رَسُولَ اللهِ ﷺ قَالَ مَا تَرَكْتُ شَيْئًا مِمَّا أَمَرَكُمُ اللهُ بِهِ إِلَّا وَقَدْ أَمَرْتُكُمْ بِهِ وَلَا تَرَكْتُ شَيْئًا مِمَّا نَهَاكُمُ اللهُ عَنْهُ إِلَّا وَقَدْ نَهَيْتُكُمْ عَنْهُ قَالَ الشَّافِعِيُّ رَحِمَهُ اللهُ فَمَا لَمْ يَكُنْ فِيهِ وَحْيٌ فَقَدْ فَرَضَ اللهُ فِي الْوَحْيِ اتِّبَاعَ سُنَّتِهِ فَمَنْ قَبِلَ عَنْهُ فَإِنَّمَا قَبِلَ بِفَرْضِ اللهِ ﷻ وَاللهُ سُبْحَانَهُ وَتَعَالَى أَعْلَمُ