فَيَرْوِي عَنْهُمَا أَوْ عَنْ أَحَدِهِمَا الْعَدَدَ مِنَ الْحَدِيثِ مِمَّا لَا يَعْرِفُهُ أَحَدٌ مِنْ أَصْحَابِهِمَا، وَلَيْسَ مِمَّنْ قَدْ شَارَكَهُمْ فِي الصَّحِيحِ مِمَّا عِنْدَهُمْ، فَغَيْرُ جَائِزٍ قَبُولُ حَدِيثِ هَذَا الضَّرْبِ مِنَ النَّاسِ، وَاللَّهُ أَعْلَمُ
Translation: A person then claims numerous reports from either teacher that no other pupils know, despite having no established participation in their sound common transmissions. Muslim does not accept reports from this type of transmitter.
Two features combine: no proven record of sound concordance and a large volume of otherwise unknown material from an extensively transmitted teacher. This does not condemn every isolated trustworthy report; it identifies a markedly different evidentiary pattern.