those scholars of hadith who hold that reason can discern moral good and evil are Abū Nasr al-Sijzī, Abū al-Qāsim Sa‘d ibn ‘Alī al-Zanjānī, and others. They stated that denying this was one of al-Ash‘arī’s unprecedented innovations.

Among Ahmad’s followers who held this view were Abū al-Hasan al-Tamīmī, Abū al-Khattāb, and others.

Indeed, they stated that this was the position of the majority of people. They also stated that the Messengers guided people to rational methods, just as they commanded obligations discernible through reason.

Thus, although they hold that reason can discern moral good and evil, they maintain that the Messengers explained and confirmed this. Likewise, although they hold that knowledge is attained through rational proofs, they maintain that the Messengers explained and confirmed this. Whatever in religion is known through reason is therefore, in their view, part of the revealed religion; and the Book—and the Sunnah—encompasses the religious truths accessible to reason.

[Al-Kalwadhānī’s discussion in his Tamhīd and Ibn Taymiyyah’s commentary]

Abū al-Khattāb said in his Tamhīd:

“The scholars of our school differed: Can reason judge things to be prohibited, permissible, obligatory, morally good, or morally evil, or not?

Abū al-Hasan al-Tamīmī said:

‘Reason does make such judgments. Thus, revealed law cannot prohibit what reason judges to be obligatory, such as gratitude to one’s benefactor, justice, fairness, fulfilling trusts, and the like. Nor can it permit what reason judges to be prohibited, such as injustice, lying, ingratitude for blessings, betrayal, and similar things.’”