Sahih Muslim #34 · Introduction

Sahih MuslimBishr bin ul-Hakam al-Abdī narrated to me
Sahih Muslim · Introduction
Sahih Muslim · مقدمة
‘By Allah, indeed it is a grave matter that the likes of you, a descendent of two Imāms of guidance – meaning Umar and Ibn Umar – is asked about a matter and you have no knowledge of it’. So [al-Qāsim] said: ‘By Allah, more grave than that according to Allah, and to whoever reflects about Allah, is to speak without knowledge or to report on authority of one who is not trustworthy’. [Ibn Uyaynah] said that Abū Aqīl Yahyā bin al-Mutawakkil witnessed them both when they said that.
وَحَدَّثَنَا عَمْرُو بْنُ عَلِيٍّ أَبُو حَفْصٍ، قَالَ سَمِعْتُ يَحْيَى بْنَ سَعِيدٍ، قَالَ سَأَلْتُ سُفْيَانَ الثَّوْرِيَّ وَشُعْبَةَ وَمَالِكًا وَابْنَ عُيَيْنَةَ عَنِ الرَّجُلِ لاَ يَكُونُ ثَبْتًا فِي الْحَدِيثِ فَيَأْتِينِي الرَّجُلُ فَيَسْأَلُنِي عَنْهُ ‏.‏ قَالُوا أَخْبِرْ عَنْهُ أَنَّهُ لَيْسَ بِثَبْتٍ ‏.‏
Reference : Sahih Muslim 34