Among these instances is what he writes in the biography of Aban ibn Taghlib al-Kufi: “A staunch Shiʿi, yet truthful. We accept his veracity, while his innovation remains upon him. Ahmad ibn Hanbal, Ibn Maʿin, and Abu Hatim declared him reliable. Ibn ʿAdi included him, noting that he was extreme in Shiʿism, and al-Saʿdi said, ‘A deviant who proclaims his view openly.’
Someone might object: How can an innovator be judged trustworthy when reliability is defined by uprightness and precision? How can a man of bidʿah (heterodoxy) be deemed upright? The answer is that innovation is of two kinds. The first is a minor innovation, such as excessive Shiʿism or even ordinary Shiʿism without excess or distortion. This was common among the Successors and those after them, together with piety, scrupulousness, and honesty. Were we to reject the hadith of such people, a large body of Prophetic reports would be lost—an obvious harm.
The second is a major innovation, such as complete rafḍ (full-blown rejectionism), extreme exaggeration therein, vilifying Abu Bakr and ʿUmar—may Allah be pleased with them both—and calling others to that. This category is afforded no consideration as proof whatsoever. Aban ibn Taghlib never disparaged the two Shaykhs at all; at most, he believed ʿAli to be superior to them. ⦗1⦘
He likewise says in the biography of Abu Nuʿaym Ahmad ibn ʿAbd Allah al-Isfahani: “One of the eminent scholars, trustworthy. He was criticized without evidence, yet that is a punishment from Allah for his partisan attack on Ibn Mandah. Al-Khatib remarked: ‘I noticed several matters in which Abu Nuʿaym was lax, among them his using the formula “He informed us” in ijazah without clarification.’
I (al-Dhahabi) said: This was a practice adopted by Abu Nuʿaym and others; it is a form of tadlis (concealed transmission).
The words of Ibn Mandah concerning Abu Nuʿaym are appalling—I dislike to relate them—and I do not accept what either of them says about the other. I know of no greater fault in the two of them than their narrating fabricated reports while remaining silent about them. I say: The criticism that contemporaries direct at one another carries no weight, especially when it appears to stem from hostility, sectarian bias, or envy—a failing from which none is safe except those whom Allah protects. I have never known an age whose scholars were free from this, save the prophets.