وَبَعْدُ يَرْحَمُكَ اللَّهُ، فَلَوْلَا الَّذِي رَأَيْنَا مِنْ سُوءِ صَنِيعِ كَثِيرٍ مِمَّنْ نَصَبَ نَفْسَهُ مُحَدِّثًا فِيمَا يَلْزَمُهُمْ مِنْ طَرْحِ الْأَحَادِيثِ الضَّعِيفَةِ وَالرِّوَايَاتِ الْمُنْكَرَةِ، وَتَرْكِهِمُ الِاقْتِصَارَ عَلَى الْأَحَادِيثِ الصَّحِيحَةِ الْمَشْهُورَةِ مِمَّا نَقَلَهُ الثِّقَاتُ الْمَعْرُوفُونَ بِالصِّدْقِ وَالْأَمَانَةِ
Translation: If there had not been such bad practice among many who appointed themselves hadith transmitters—failing to set aside weak and anomalous reports and to confine public transmission to sound, well-known reports from trustworthy people—then the requested task would not have been so easy to undertake.
The construction “fa-lawlā … la-mā sahula” expresses a counterfactual condition. Muslim criticizes indiscriminate dissemination despite knowledge of defects, not legitimate scholarly study of weak reports for criticism and analysis.