His statement on the prostration that occurs within the prayer reads: “Al-Ḥākim transmitted—declaring it authentic according to the criteria of the Two Shaykhs—from Ibn ʿUmar that the Prophet ﷺ prostrated in the first rakʿah of the ẓuhr prayer, whereupon his Companions concluded that he had recited Tanzīl al-Sajdah (Surah al-Sajdah).”

I say: This ḥadith is not sound, even though al-Ḥākim graded it ṣaḥīḥ, al-Dhahabī concurred, and Ibn Ḥajar in Fatḥ al-Bārī, together with al-Qasṭallānī and al-Zurqānī, followed their assessment. They looked only at the outward form of the chain, for al-Ḥākim related it through Yaḥyā ibn Saʿīd → Sulaymān al-Taymī → Abū Majliz → Ibn ʿUmar.

On the surface this isnād appears sound, but it is in fact broken. Someone other than Yaḥyā ibn Saʿīd stands between the narrators, for Yazīd ibn Hārūn said: “Sulaymān al-Taymī narrated to us from Abū Majliz”—and he added—“yet he did not hear it from Abū Majliz”—“from Ibn ʿUmar.” Al-Bayhaqī, Aḥmad, Abū Dāwūd, and al-Ṭaḥāwī all recorded this wording.

Muʿtamir ibn Sulaymān made the matter clearer by identifying an unknown intermediary between Sulaymān al-Taymī and Abū Majliz. He reported: “From my father, from a man called Umayyah, from Ibn ʿUmar.” This version was also transmitted by al-Bayhaqī and Abū Dāwūd.

This Umayyah is unanimously deemed unknown; the report therefore hinges on an anonymous narrator, and a narration that comes through an unidentified source carries no weight among the experts of ḥadith.

Ibn Ḥajar himself took note of this defect in his work al-Talkhīṣ. After mentioning the route through Umayyah he wrote: “Yet al-Ḥākim’s wording suppresses the name, and al-Ṭaḥāwī’s version shows that this indicates Sulaymān al-Taymī was practicing tadlīs.”

For that reason Imām Aḥmad did not act upon this ḥadith, as Abū Dāwūd relates in his Masāʾil