38 – ʿAbd Allāh b. Zayd (may Allah be pleased with him) said, “The Prophet ﷺ was brought two-thirds of a mudd of water, whereupon he began to rub his forearms.” Recorded by Aḥmad; Ibn Khuzaymah declared it authentic. (1)

Degree of authenticity:
The ḥadīth is ṣaḥīḥ. Abū Zurʿah al-Rāzī and Ibn Khuzaymah classed it as sound, and it was also reported by al-Ḥākim and Ibn Ḥibbān. Abū Dāwūd (94) likewise transmitted—from Umm ʿImārah al-Anṣāriyyah with a good chain—that “he ﷺ performed ablution from a vessel containing about two-thirds of a mudd,” and al-Bayhaqī (1/196) narrated it from ʿAbd Allāh b. Zayd. In sum: ʿUbādah b. Tamīm related the report both from ʿAbd Allāh b. Zayd and from Umm ʿImārah; he is reliable, so both versions are authentic.

Vocabulary:
• mudd: a legal measure equal to one quarter of the prophetic saʿ; roughly 750 mL.
• rubbed: he stroked the body part with his hand so the water would reach every fold.
• forearms: the portion of the arm from the elbow to the hand; plural adhruʿ.

Points derived from the ḥadīth:
1 – It is permissible to perform ablution with two-thirds of a mudd. A mudd is one quarter of the prophetic saʿ, and the prophetic saʿ is about 3 liters. Al-Qāmūs states: it is what fills the two joined palms of a person of average build when he stretches them out.