Sahih Muslim Introduction 10
Abūt-Tāhir Ahmad bin Amr bin Sarh narrated to me, he said, Ibn Wahb narrated to us, he said, Mālik said to me:
‘Know that a man who relates everything he hears is not safe, and he can never be an Imām, as long as he narrates everything he hears’.
وَحَدَّثَنِي أَبُو الطَّاهِرِ، أَحْمَدُ بْنُ عَمْرِو بْنِ عَبْدِ اللَّهِ بْنِ عَمْرِو بْنِ سَرْحٍ قَالَ أَخْبَرَنَا ابْنُ وَهْبٍ، قَالَ قَالَ لِي مَالِكٌ اعْلَمْ أَنَّهُ لَيْسَ يَسْلَمُ رَجُلٌ حَدَّثَ بِكُلِّ مَا سَمِعَ وَلاَ يَكُونُ إِمَامًا أَبَدًا وَهُوَ يُحَدِّثُ بِكُلِّ مَا سَمِعَ ‏.‏