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حَدَّثَنَا أَبُو جَعْفَرٍ، مُحَمَّدُ بْنُ الصَّبَّاحِ حَدَّثَنَا إِسْمَاعِيلُ بْنُ زَكَرِيَّاءَ، عَنْ عَاصِمٍ الأَحْوَلِ، عَنِ ابْنِ سِيرِينَ، قَالَ لَمْ يَكُونُوا يَسْأَلُونَ عَنِ الإِسْنَادِ، فَلَمَّا وَقَعَتِ الْفِتْنَةُ قَالُوا سَمُّوا لَنَا رِجَالَكُمْ فَيُنْظَرُ إِلَى أَهْلِ السُّنَّةِ فَيُؤْخَذُ حَدِيثُهُمْ وَيُنْظَرُ إِلَى أَهْلِ الْبِدَعِ فَلاَ يُؤْخَذُ حَدِيثُهُمْ ‏.‏

Abū Ja’far Muhammad bin us-Sabbāh narrated to us, Ismā’īl bin Zakariyyā’ narrated to us, on authority of Āsim il-Ahwal, on authority of Ibn Sīrīn that he said: ‘They would not ask about the chains of narration, and when the Fitnah occurred, they said: ‘Name for us your men’. So Ahl us-Sunnah would be regarded, and their Ḥadīth were then taken, and Ahl ul-Bi’dah would be regarded, and their Ḥadīth were not taken’.

Sahih Muslim Introduction 27 https://sunnah.com/muslim/introduction/26