it is easy, the reference is given. you can download tahzib ut tahzib from here , and an old version from here. here is the quote from the old version above and it is easy to explain because it is established that all the companions are superior (afDal) from rest of the ummah. There were many companions who did not live long after their Islam, yet they are superior than all the tabi'in, atba' tabi'in, and the entire ummah. being a companion (saha'abi) is a faDl which no other ummati can get, no matter, however pious and knowledgeable that ummat is. لاتسبوا أصحابي فلو أن أحدکم أنفق مثل أحد ذهبا ما بلغ مدّ أحدهم ولا نصیفه : بخاري # 3673 کان بین خالد بن ولید وبین عبدالرحمن بن عوف شيء فسبه خالد فقال رسول اللهﷺ:«لا تسبوا أحدا من أصحابي فإن أحدکم لو أنفق مثل أحد ذهبا مابلغ مد أحدهم ولا نصیفه : مسلم # 2541 these, and other ahadith, are clear evidences that the companions have a special faDl near Allah subh'anu wa ta'ala which no other mo'min after them can get. so, ibn u'yainah did not mean to belittle the companions raDi Allahu a'anhum, rather he acknowledged their superiority over ibn al mubarak alaihi rah'mah.
Can a brother check, the following, "Sufyan ibn ‘Uyaynah said, “I looked into in the matter of the Sahabah and I did find any virtue in them over Ibn al-Mubarak except their companionship of the Prophet (Allah bless him and grant him peace) and their battles with him.” (Tahdhib al-Tahdhib 5:385) Has this quote been translated accurately? This quote as it is, without, attribution, to Imam Sufyan, Rahmat Allahi Ta'alâ alayh, is unacceptable, and extremist?: 2. ‘Abd Allah ibn al-Mubarak (118 – 181), also a narrator of the Six, and one of the Imams of the Atba’ Tabi’in whose merits are innumerable. Sufyan ibn ‘Uyaynah said, “I looked into in the matter of the Sahabah and I did find any virtue in them over Ibn al-Mubarak except their companionship of the Prophet (Allah bless him and grant him peace) and their battles with him.” (Tahdhib al-Tahdhib 5:385) He was an undisputed authority in hadith. https://www.google.co.uk/amp/s/note...-on-imam-abu-hanifahs-excellence-in-fiqh/amp/