Sahih Muslim 14656
In-book no 7379وَحَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، قَالَ سَمِعْتُ عَبْدَ الرَّحْمَنِ بْنَ مَهْدِيٍّ، يَقُولُ لاَ يَكُونُ الرَّجُلُ إِمَامًا يُقْتَدَى بِهِ حَتَّى يُمْسِكَ عَنْ بَعْضِ مَا سَمِعَ .
Muhammad bin ul-Muthannā narrated to us, he said I heard Abd ar-Rahman bin Mahdī saying: ‘A man cannot be an Imām whose example is followed until he withholds from some of what he hears’.