How is it permissible for the Prophet (peace be upon him) and his wife to perform ghusl from a single vessel, even though dipping a hand in water renders it used and unsuitable for ghusl?

Aisha's ghusl (ritual bath) with the Prophet, peace and blessings be upon him, from a single vessel is established and authentic. Jurists have differed regarding a small amount of water into which a hand is dipped with the intention of removing ritual impurity: does it become merely pure (tahir) or remain purifying (tahoor)?

Shaykh al-Islam Ibn Taymiyyah holds that regarding a person in a state of major ritual impurity (junub) dipping their hand into water, there are two opinions as to whether it renders the water used or not. It has been authentically reported that the Prophet, peace and blessings be upon him, scooped water from a vessel while in a state of janabah. This does not contradict the view that water into which a hand is dipped with the intention of removing ritual impurity becomes pure but not purifying. The hadith can therefore be interpreted as referring to the mere intention of scooping water.

Dr. Wahbah al-Zuhayli is of the opinion that a small amount of water does not become used (musta'mal) if a person performing ablution (wudu') scoops from it when washing their hands, because the scooper's intention in dipping their hand was only to scoop water.