Beginning of asking narrators to name their sources after the "Fitnah"

‘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’.

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