Under the heading “Water and its Classifications,” he writes under entry 3: “On the strength of the ḥadīth of ʿAlī (may Allah be pleased with him) in which the Messenger of Allah ﷺ called for a bucket of Zamzam water, drank from it, and performed wuḍūʾ; it was narrated by Aḥmad.”

I say: Two observations must be made here.

First: the report is not found in the Musnad of Aḥmad himself; it appears only among the additional narrations recorded by his son (1/76).

Second: prefacing it with the passive formula “it is narrated”—which usually hints at weakness—contradicts the thirteenth principle set out earlier, for the isnād of the ḥadīth is ḥasan, as clarified in Irwāʾ al-Ghalīl, no. 13. Aḥmad Shākir (may Allah have mercy on him) likewise declared it ṣaḥīḥ in his commentary on the Musnad (2/19/564), explicitly noting that it belongs to the supplements.

He then cited the ḥadīth, “When the water reaches two qullahs it does not carry filth,” saying: “It is narrated by the Five; its chain and text are internally inconsistent … .”

I reply: Not at all. It is an authentic ḥadīth, and a number of scholars—among them Abū Jaʿfar al-Ṭaḥāwī the Ḥanafī—have graded it sound. The inconsistency to which he alluded occurs only in some of its weak routes, as I have shown in Ṣaḥīḥ Abī Dāwūd, 56–58, and noted in Irwāʾ al-Ghalīl, 23 and 172.

Granted, the implication of this ḥadīth does clash with the general wording of the ḥadīth of Abū Saʿīd: “Water is pure; nothing renders it impure.” That latter text is the one to be relied upon in this chapter, as Ibn al-Qayyim explained in Tahdhīb Sunan Abī Dāwūd. Whoever seeks a thorough examination should consult it, for it contains a rare and important discussion. See also al-Sayl al-Jarrār by al-Shawkānī, 1/55.