Sunan Abi Dawud, Hadith 4607

Ibn ‘Awn said: If we learnt that the remark of al-Hasan would reach the extent that it has reached, we would write a book for his withdrawal and call witnesses to him; but we said: This is a remark that surprisingly came out (from him) and it will not be transmitted to others.

حَدَّثَنَا ابْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالاَ حَدَّثَنَا مُؤَمَّلُ بْنُ إِسْمَاعِيلَ، حَدَّثَنَا حَمَّادُ بْنُ زَيْدٍ، عَنِ ابْنِ عَوْنٍ، قَالَ لَوْ عَلِمْنَا أَنَّ كَلِمَةَ، الْحَسَنِ تَبْلُغُ مَا بَلَغَتْ لَكَتَبْنَا بِرُجُوعِهِ كِتَابًا وَأَشْهَدْنَا عَلَيْهِ شُهُودًا وَلَكِنَّا قُلْنَا كَلِمَةٌ خَرَجَتْ لاَ تُحْمَلُ ‏.‏

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also referenced under: Hadith 4624 (DarusSalam)