The Messenger of Allah ﷺ said, "The extremists are doomed." He said it three times.
قال رسول الله ﷺ: هلك المتنطعون. قالها ثلاثا.
Muslim narrated it in the Book of Knowledge (2670) from Abu Bakr bin Abu Shayba, who said, Hafs bin Ghiyath and Yahya bin Saeed narrated to us, from Ibn Jurayj, from Sulayman bin Atiq, from Talq bin Habib, from Ahnaf bin Qays, from Abdullah (that is, Ibn Masud), and he related the hadith.The mutanattiun are those who go to excess and overstep the limits in their words and deeds.On this subject there is also what was reported from Muawiya, that the Prophet ﷺ forbade aghlutat (contrived, difficult questions). Abu Dawud narrated it (3656) from Ibrahim bin Musa Razi, from Isa bin Yunus, from Uzai, from Abdullah bin Saad, from Sanabihi, from Muawiya, who related it.Abdullah bin Saad is Ibn Farwa Bajali, the client of theirs from Damascus. No one has affirmed him as reliable. Ibn Hibban only mentioned him in Ath-Thuqat and said, "He makes mistakes." Abu Hatim said, "He is unknown."Through this same route it was narrated by Imam Ahmad (5/435), Tabarani in Al-Kabir (19/982), Khatib in Al-Faqih wal-Mutafaqqih (635), and Bayhaqi in Al-Madkhal (304).As for aghlutat, Uzai said it means difficult and hard questions. Khattabi said, "He forbade that scholars should be confronted with hard questions in which error is common, so that they might be tripped up by them and their opinion on the matter discredited. This contains a disapproval of going too deep and overburdening oneself with what a person has no need of in a question, and it establishes the obligation to refrain from answering what the one being asked has no knowledge of."See Maalim Sunan, and his Gharib al-Hadith (1/354).