Shaykh Hamza Yusuf states the religion falls apart without the Sunnah, he mentions that without Hadith one cannot know how to pray, perform Hajj of Umrah. Hamza Yusuf states it's Kufr to deny Mutawatir Hadith.
According to Dr Jonathan Brown the Quran-Only approach is a modern movement which is inconsistent and intellectually dishonest.
Hamza Yusuf and Dr Jonathan Brown On the Deviant Group of Quran Onlyists
What is Isnad in Hadith Studies
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