Ibn Sirin reported,

They did not used to ask about the chain of narration, but when the civil strife occurred they began to say, "Name to us your narrators." So Some men of the Sunnah would be examined and their hadith accepted, and Some men of innovation would be examined and their hadith rejected.

Muslim 27

Sahih

حدثنا أبو جعفر، محمد بن الصباح حدثنا إسماعيل بن زكرياء، عن عاصم الأحول،

عن ابن سيرين، قال

لم يكونوا يسألون عن الإسناد، فلما وقعت الفتنة قالوا سموا لنا رجالكم فينظر إلى أهل السنة فيؤخذ حديثهم وينظر إلى أهل البدع فلا يؤخذ حديثهم.

مسلم 27صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Introduction
Chapter
Isnad is part of the religion, narration is only to be taken from trustworthy narrators, criticizing narrators for what is actually in them is permissible and even obligatory, and this is not from prohibited backbiting but rather from defending the noble Shariah
Numbering
Darussalam 27
Muslim 27