Ḥammād ibn Salamah [say]: “I heard al-Ḥajjāj al-Aswad narrating to Thābit, from Abū al-Ṣiddīq, from Abū Dharr, from the Prophet, peace and blessings be upon him, who said: ‘You are in an age in which whoever neglects ...’”—a wording similar to it.

I say: Aḥmad transmitted this with a continuous chain in al-Musnad (5/155): Muʾammal narrated to us; Ḥammād narrated to us; al-Ḥajjāj al-Aswad narrated to us—Muʾammal said: “He was a righteous man”—who said: “I heard Abū al-Ṣiddīq narrating to Thābit al-Bunānī, from a man, from Abū Dharr,” with the same report.

I say: Aḥmad thus added “from a man” to its chain of transmission, thereby impairing it. Al-Haythamī therefore deemed it defective on this account (1/127), saying: “Aḥmad narrated it, and it contains an unnamed man.”

I say: In my view, this addition came from Muʾammal, who is Muʾammal ibn Ismāʿīl al-Baṣrī, for he had poor retention, as stated in al-Taqrīb. He would therefore be inconsistent in this regard: at times he would mention it, as preserved in Aḥmad’s version, and at other times omit it, as in the previously cited narration of Isḥāq from him. Isḥāq was the imām Ibn Rāhawayh. This latter version is correct, since it accords with the narration of ʿĪsā ibn Yūnus, in which, as you have seen, there is no discrepancy. Both ʿAlī ibn Khushram and Ibrāhīm ibn Mūsā—Abū Isḥāq al-Farrāʾ—agreed upon it, and both were trustworthy narrators used by al-Bukhārī and Muslim.

This shows that the hadith has an authentic chain of transmission. All of its narrators are trustworthy, apart from al-Ḥajjāj ibn Abī Ziyād—yet he too is trustworthy, as Aḥmad and Ibn Maʿīn said, and later al-Dhahabī stated in Talkhīṣ al-Mustadrak (4/332). Al-Dhahabī gave him an excessively brief and inadequate biographical entry in al-Mīzān, unlike al-Ḥāfiẓ in al-Lisān; consult it. He is the narrator of the previously cited hadith, “The Prophets are alive in their graves” (621), so see his biographical entry there.

As for al-Ḥajjāj’s uncertainty between Abū Naḍrah and Abū al-Ṣiddīq, it does not affect the soundness of the chain, since his uncertainty was between two trustworthy narrators. Take note.