Amr bin Alī and Hasan al-Hulwānī narrated to me, both of them on authority of Affān bin Muslim, he said:
‘We were near Ismā’īl bin Ulayyah, and a man narrated on authority of another man, so I said: ‘Indeed this is not reliable (Thabt)’. So the man said: ‘Are you backbiting him?’ Ismā’īl said: ‘He is not backbiting him; rather he is judging him unreliable’.

حَدَّثَنِي عَمْرُو بْنُ عَلِيٍّ، وَحَسَنٌ الْحُلْوَانِيُّ، كِلاَهُمَا عَنْ عَفَّانَ بْنِ مُسْلِمٍ، قَالَ كُنَّا عِنْدَ إِسْمَاعِيلَ ابْنِ عُلَيَّةَ فَحَدَّثَ رَجُلٌ، عَنْ رَجُلٍ، فَقُلْتُ إِنَّ هَذَا لَيْسَ بِثَبْتٍ . قَالَ فَقَالَ الرَّجُلُ اغْتَبْتَهُ . قَالَ إِسْمَاعِيلُ مَا اغْتَابَهُ . وَلَكِنَّهُ حَكَمَ أَنَّهُ لَيْسَ بِثَبْتٍ .