Muslim

And the one who made the claim, with which we began the discussion regarding the narration, claimed—based on his statement and the report of his poor judgment—that every isnad of a hadith in which it is so-and-so from so-and-so, and it is established by knowledge that they were both in the same era and it is possible that the narrator heard the hadith from the one he narrates from and received it directly from him, yet we do not know of any instance of him hearing from him, nor have we found in any of the narrations that they ever met or exchanged hadith between them, then the proof is not established for him by every report that comes in this manner until he has knowledge that they met at least once in their lifetimes or exchanged hadith between them, or a report comes clarifying that they met and encountered each other at least once in their lifetimes or more. If he does not have knowledge of that, and no authentic narration comes informing that this narrator from his companion met him even once and heard something from him, then in his transmission of the report from the one he narrates from, there is no knowledge of that, and the matter as we have described is not a proof, and the report for him is considered suspended until it is established that he heard from him something of the hadith, whether little or much, in a narration similar to what has been mentioned.