Abu Bakr al-Bazzar: Of utmost piety
Abu Hatim ibn Hibban al-Busti: Among the leaders of his time in worship, excellence, piety, asceticism, firmness in the Sunnah, and severity towards the people of innovation. He saw people but did not hear anything from them. He narrated from Al-Qasim, Al-Hasan, and Ibn Sirin, and narrated from him Ibn al-Mubarak and the people of Basra.
Ahmad ibn Shuayb al-Nasa'i: Trustworthy, reliable, and once: Trustworthy, Upright
Ahmad ibn Salih al-Jili: Trustworthy, righteous man
Ismail ibn Ulayah: He was asked about the hadith scholars of Basra, so he mentioned among them: Abdullah ibn Aun
Ibn Abi Hatim al-Razi: Trustworthy
Ibn Hajar al-'Asqalani: Trustworthy, Upright, Excellent, one of the peers of Ayyub in knowledge, deeds, and age
Ibn Abd al-Barr al-Andalusi: Upright
Al-Awza'i: When Ibn Aun and Sufyan died, people became equal
Al-Dhahabi: One of the prominent figures
Shubah ibn al-Hajjaj: Trustworthy, for I prefer to hear a hadith from Ibn Aun than from anyone else
Abd al-Rahman ibn Mahdi: There was no one in Iraq more knowledgeable of the Sunnah than him
Uthman ibn Abi Shaybah: Trustworthy, his book is sound
Uthman ibn Muslim al-Batti: My eyes have never seen anyone like him
Ali ibn al-Madini: There is no one among the people like Ibn Aun and Ayyub, he gathered what no one else gathered
Isa ibn Yunus al-Sabi'i: He was asked about Abdullah ibn Aun and Hisham al-Qardusi, he said: Ibn Aun was the more knowledgeable of the two
Qurra ibn Khalid al-Sadusi: We used to be amazed by the piety of Ibn Sirin, then we forgot him because of Ibn Aun
Muhammad ibn Sa'd, the scribe of al-Waqidi: Trustworthy
Muhammad ibn Abdullah al-Makhrami: I have not seen anyone better than Ibn Aun
Hisham ibn Hassan al-Qardusi: My eyes have never seen anyone like him
Yahya ibn Ma'in: Upright, and once he said: He is trustworthy in everything, and once he said: Ibn Aun is better than Amr ibn Qays al-Mala'i