Sahih Muslim Introduction 38
Muhammad bin Abd Allah bin Quhzādh, from the people of Marw, narrated to me, he said Alī bin Husayn bin Wāqid informed me, he said Abd Allah bin al-Mubārak said, I said to Sufyān ath-Thawrī:
‘Indeed Abbād bin Kathīr, about whose condition you are aware, when he related [narrations] he introduced a grave matter- do you believe that it should be said to the people ‘Do not take from him?’ Sufyān said: ‘Indeed!’ Abd Allah [bin al-Mubārak] said: ‘So when I was in an assembly and Abbād was mentioned there, I praised him regarding his Dīn and said: ‘Do not take from him.’ Muhammad said, Abd Allah bin Uthmān narrated to us, he said, my father said, Abd Allah bin al-Mubārak said: ‘I ended up in an assembly of Shu’bah, and he said: ‘This is Abbād bin Kathīr so be warned against him.’
وَحَدَّثَنِي مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ قُهْزَاذَ، - مِنْ أَهْلِ مَرْوَ - قَالَ أَخْبَرَنِي عَلِيُّ بْنُ حُسَيْنِ بْنِ وَاقِدٍ، قَالَ قَالَ عَبْدُ اللَّهِ بْنُ الْمُبَارَكِ قُلْتُ لِسُفْيَانَ الثَّوْرِيِّ إِنَّ عَبَّادَ بْنَ كَثِيرٍ مَنْ تَعْرِفُ حَالَهُ ‏.‏ وَإِذَا حَدَّثَ جَاءَ، بِأَمْرٍ عَظِيمٍ فَتَرَى أَنْ أَقُولَ، لِلنَّاسِ لاَ تَأْخُذُوا عَنْهُ قَالَ سُفْيَانُ بَلَى ‏.‏ قَالَ عَبْدُ اللَّهِ فَكُنْتُ إِذَا كُنْتُ فِي مَجْلِسٍ ذُكِرَ فِيهِ عَبَّادٌ أَثْنَيْتُ عَلَيْهِ فِي دِينِهِ وَأَقُولُ لاَ تَأْخُذُوا عَنْهُ ‏.‏ 
وَقَالَ مُحَمَّدٌ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ عُثْمَانَ، قَالَ قَالَ أَبِي قَالَ عَبْدُ اللَّهِ بْنُ الْمُبَارَكِ انْتَهَيْتُ إِلَى شُعْبَةَ فَقَالَ هَذَا عَبَّادُ بْنُ كَثِيرٍ فَاحْذَرُوهُ ‏.‏