The Book on Government
حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا مُحَمَّدُ بْنُ فُضَيْلٍ، عَنْ عَاصِمٍ، بِهَذَا الإِسْنَادِ قَالَ فَلَقِيتُ أَخَاهُ فَقَالَ صَدَقَ مُجَاشِعٌ . وَلَمْ يَذْكُرْ أَبَا مَعْبَدٍ .Another version of the tradition transmitted on the authority of Asim has the same wording but does not mention the name of Abu Ma'bad
From Sahih Muslim, whose reports the scholars accept as authentic.