al-Baghawī said: "This is a ṣaḥīḥ ḥadīth." Mūsá ibn Dāwūd, who is trustworthy but has errors, and ʿAlī ibn ʿAyyāsh, who is reliable and firm, corroborated him with Abū ʿAwānah. Saʿīd ibn Sulaymān, who is al-Ḍabbī al-Wāsiṭī, a trustworthy ḥāfiẓ, corroborated him with al-Bayhaqī. I say: All of them mentioned in the ḥadīth: "night." ʿAlī ibn Naṣr al-Jahḍamī differed from them: he narrated from Layth ibn Saʿd with it; except that he said: "day" instead of "night." Muslim narrated it alone, and added at the end: "Layth said: The non-Arabs among us avoid that in December." al-Nawawī reconciled the two narrations: "night" and "day" by saying: "There is no contradiction between them, as neither negates the other." I say: It should have been so; were it not for our investigation of the narrators from Layth ibn Saʿd, which indicated the irregularity of the narration: "day"; because al-Jahḍamī was alone in narrating it, differing from the five reliable narrators who reported it with the first wording. Their agreement on it indicates al-Jahḍamī's error and the irregularity of his narration, and irregularity is established with less than this; as is known to those experienced in this noble science. This irregularity resembles what occurred in the ḥadīth of ʿUmar; that he vowed in the pre-Islamic period to perform iʿtikāf