This is a contradiction on his part, for he declared this Muʿāwiyah weak and deemed his shaykh unknown, as will be shown.
Al-Ḥāfiẓ also said in Taghlīq al-Taʿlīq 5/21–22, after presenting the three lines of transmission for the report from ʿAbd al-Raḥmān ibn Ghanm:
“This is a sound ḥadīth; it contains neither hidden flaw nor valid criticism. Abū Muḥammad Ibn Ḥazm tried to discredit it by alleging a break between al-Bukhārī and Ṣadaqah ibn Khālid and by pointing to the variation in the name of Abū Mālik. Yet, as you can see, I have produced it through nine transmitters from Hishām with uninterrupted chains, among them al-Ḥasan ibn Sufyān, ʿAbdān, and Jaʿfar al-Firyābī—men who are reliable masters.”
As for the discrepancy in the Companion’s kunyah, all Companions are upright and trustworthy.
It further seems to me that, when the critic enamoured with weakening authentic ḥadīths found no room to cling to this defect because of its obvious invalidity, he invented another, even flimsier in the eyes of the scholars—namely, the claim that ʿAṭiyyah ibn Qays, upon whom Muslim relied and whom others declared reliable, is “unknown.” This is a false allegation, unprecedented before him, as was clarified on pp. 43–44; there is therefore no need to repeat the refutation, though drawing attention to it here is beneficial.
I have already cited two additional chains for the ḥadīth from ʿAbd al-Raḥmān ibn Ghanm; one is the route of Muʿāwiyah ibn Ṣāliḥ mentioned above. Ibn Ḥazm faulted it, saying in his epistle, p. 97: “Muʿāwiyah ibn Ṣāliḥ is weak, and Mālik ibn Abī Maryam—no one knows who he is.” He also criticised it in al-Muḥallā 9/57 on the ground of Muʿāwiyah alone, and this impugnment is nothing but unfair bias.