Is narration from people of innovation accepted?

A question of jarh wa-ta'dil: if a truthful, retentive transmitter holds an innovation in belief, is his hadith written down and relied on? Al-Dhahabi treats the matter in the introduction to Mizan al-I'tidal, and counts among the grades of men in his book "the trustworthy and firm who hold an innovation". ¹

Asim al-Ahwal reported from Muhammad ibn Sirin that people did not ask about the chain of transmission, but when the strife came they began asking for the men to be named. ¹ Those who were of the people of the Sunna had their hadith taken, and those who were of the people of innovation had their hadith left. ² Al-Dhahabi then reports al-Hasan forbidding sitting with the people of caprice and hearing from them, and adds that softening a man for innovation is a wide subject that this is not the place to settle. ²

Al-Dhahabi poses the question openly in the entry on Aban ibn Taghlib of Kufa: how could an innovator be declared trustworthy, when the definition of a trustworthy man is probity and exactness? ² Ahmad ibn Hanbal, Ibn Ma'in and Abu Hatim had declared Aban trustworthy, while Ibn Adi said he was extreme in Shi'ism and al-Sa'di called him an open deviant. ² His answer is that innovation is of two kinds:

• Lesser innovation: such as Shi'ism with or without excess and without zealotry, which was widespread among the Successors and their followers together with religion, piety and truthfulness; were the hadith of such men rejected, a body of the prophetic reports would be lost, which he regards as a plain harm. ^{2 3}
• Greater innovation: such as complete rafd and excess in it, disparaging Abu Bakr and Umar and calling others to that; men of this kind, in his view, are not relied on at all, and he holds that lying and dissimulation prevail among them. ³

He distinguishes the extremist of the early generations — one who spoke against Uthman, al-Zubayr, Talha, Mu'awiya and some of those who fought Ali, and insulted them — from the extremist of his own time, who declares these men unbelievers and disowns the two shaykhs. ³

• At the start of part three al-Dhahabi describes Ubayd Allah ibn Ibrahim al-Ansari as "holding together, but one of the shaykhs of the Shi'a", and Ubayd Allah ibn Ahmad ibn Ma'ruf, chief judge, as declared trustworthy by al-Khatib "but a Mu'tazili". ⁴
• Of Ikrima, client of Ibn Abbas, he says that Ikrima was criticised for his opinion, not his memory, being accused of the Kharijite view, and that al-Bukhari relied on him while Muslim avoided him except for a little, paired with others. ⁵ He reports Ahmad saying that Ikrima was among the most learned of men but held the view of the Sufriyya. ⁶
• Of Muhammad ibn Ishaq he reports Ibn Numayr saying that he was charged with the Qadari view and was the farthest of men from it, Abu Dawud calling him a Qadari Mu'tazili, and Ibn Uyayna saying he had heard no one speak against him except about qadar. ^{7 8} He also records that Ibn Ishaq was seen flogged over qadar, flogged by the governor Ibrahim ibn Hisham. ⁹

Three centuries before al-Dhahabi, al-Khatib al-Baghdadi gave a chapter of al-Kifaya to "taking from the people of innovation and caprice and relying on their reports". ¹⁰ He states that scholars differed on hearing from innovators such as the Qadariyya, the Kharijites and the Rafida: ¹⁰

• One group of early scholars refused, since such men are unbelievers for those who declare interpreters unbelievers and sinners for those who do not; among those who did not narrate from them was Malik ibn Anas. ¹⁰
• Another group accepted the reports of people of caprice not known to consider lying lawful, among them al-Shafi'i, who said that the testimony of the people of caprice is accepted except for the Khattabiyya of the Rafida, who consider false testimony for their own allowed; this was also reported of Ibn Abi Layla, Sufyan al-Thawri and Abu Yusuf. ¹⁰
• Many scholars accepted the reports of those people of caprice who did not propagate their views, but not of propagandists; among them was Ahmad ibn Hanbal. ¹¹
• Some transmitters and theologians said that all reports of the people of caprice are accepted, even if they are unbelievers or sinners by interpretation. ¹¹

He cites warnings such as "this knowledge is religion, so look at whom you take it from", from al-Dahhak and Ibn Sirin, and the report of a repentant Kharijite shaykh: when we fancied something, we turned it into a hadith. ^{11 12} He then challenges the distinction between the interpreter and the deliberate sinner, and says that what one may rely on in allowing their reports is the Companions' well-known acceptance of the Kharijites' reports and testimony, and the continued practice of the Successors and those after them, because they saw how such men sought truthfulness and dreaded lying. ^{13 14} He lists men whose narration was relied on: Imran ibn Hittan of the Kharijites, Amr ibn Dinar, Ikrima who was an Ibadi, Ibn Abi Najih who was a Mu'tazili, Qadaris such as Hisham al-Dastuwa'i and Sa'id ibn Abi Aruba, Murji'is such as Mis'ar ibn Kidam, and Shi'is such as Abd al-Razzaq ibn Hammam — this became, he says, akin to their consensus, "the greatest proof in this matter". ¹⁴ He reports al-Shafi'i saying he had seen none of the people of caprice more given to false testimony than the Rafida, and Abu Yusuf accepting the testimony of the truthful among them except the Khattabiyya and the Qadaris who say God does not know a thing until it happens. ¹⁵