Abdullah ibn Mubarak went to Kufa and did debate with them regarding Nabeedh, they started taking the names of Tabiyeen like Ibraheem i.e. they used to consider it halal, do you think they were drinking haram? Ibn al Mubarak refuted (with ahadeeth and sahaba) and said: What do you say about Ata, tawus and other people of Hijaz? they said they were the best of people. Ibn al Mubark again asked, and what do you say regarding 2 dirhams against 1 dirham? they said it is haram. He replied then they (Ata and Tawus etc) used to consider it halal, do you think they ate haram? [Masaail Imam Ahmad wal Ishaq 9/4845-4847 no. 3537] Scan:
Imam ash-Shatibi mentioned that Ibn al Mubarak said:
فَرُبَّ رَجُلٍ فِي الْإِسْلَامِ مَنَاقِبُهُ كَذَا وَكَذَا وَعَسَى أَنْ يَكُونَ مِنْهُ زَلَّةٌ، أَفَلِأَحَدٍ أَنْ يَحْتَجَّ بِهَا؟
Sometimes a person has virtues in Islam but still he can make mistakes, does that mistake can be taken as an evidence? [ash-Shatibi in al Muwafiqaat 5/137-138, Ibn Taymiyah in Ibtaal at-Tahleel 203, 204]
After quoting this debate ash-Shatibi said:
وَالْحَقُّ مَا قَالَ ابْنُ الْمُبَارَكِ، فَإِنَّ اللَّهَ تَعَالَى يَقُولُ: {فَإِنْ تَنَازَعْتُمْ فِي شَيْءٍ فَرُدُّوهُ إِلَى اللَّهِ وَالرَّسُول} الْآيَةَ .
Truth is with the statement of Ibn al Mubarak as Allah says:
And if you disagree over anything, refer it to Allah and the Messenger [an-Nisa:59] [al Muwafiqaat by ash-Shatibi 5/137-138]
also narrated by al Bayhaqi a short version in which Ibn al Mubarak said:
رأيت أعجب من هؤلاء أحدثهم عن رسول الله صلى الله عليه وسلم ، وعن أصحابه والتابعين ؛ فلم يعبأوا به ، وأذكر عن إبراهيم فنكسوا رؤوسهم
I am surprised that I narrate ahadeeth of Prophet peace be upon him, Sahaba and Tabiyeen which does not concern you, and you take the name of Ibraheem [Sunan al Kubra 8/298]