قَالَ مُسْلِمٌ: وَسَمِعْتُ عُبَيْدَ اللَّهِ بْنَ عُمَرَ الْقَوَارِيرِيَّ يَقُولُ: سَمِعْتُ حَمَّادَ بْنَ زَيْدٍ يَقُولُ لِرَجُلٍ بَعْدَ مَا جَلَسَ مَهْدِيُّ بْنُ هِلَالٍ بِأَيَّامٍ: مَا هَذِهِ الْعَيْنُ الْمَالِحَةُ الَّتِي نَبَعَتْ قِبَلَكُمْ؟ قَالَ: نَعَمْ، يَا أَبَا إِسْمَاعِيلَ.
Translation: Muslim adds, in his own voice, that he heard al-Qawārīrī report: a few days after Mahdī b. Hilāl began holding sessions, Ḥammād b. Zayd asked a man, “What is this salty spring that has appeared among you?” The man acknowledged the remark, addressing him as Abū Ismāʿīl.
“The salty spring” is a metaphor for a seemingly available but unsuitable source. The critic’s negative assessment of the gathering does not by itself identify and settle the authenticity of an unspecified individual report.
Beyond the metaphor, al-Nawawī records an explicit rijāl judgment about this particular Mahdī b. Hilāl: «فَهَذَا مُتَّفَقٌ عَلَى ضَعْفِهِ» (“his weakness is agreed upon”). He also cites al-Nasāʾī: «هُوَ بَصْرِيٌّ مَتْرُوكٌ» (“he is a Basran narrator whose reports are abandoned”). Thus Ḥammād’s image alone does not grade every unspecified matn, but the independent, named criticism does establish a specific adverse assessment of Mahdī. A metaphorical warning and an explicit technical verdict are distinct kinds of evidence.