Concerning a person in a state of major ritual impurity bathing in standing water:
As for the sound ḥadīth related by Anas:
“A Bedouin came to one side of the mosque and urinated there. The people cried out at him, but the Messenger of Allah—peace and blessings be upon him—said, ‘Leave him.’ When he had finished, the Messenger of Allah—peace and blessings be upon him—ordered that a bucket of water be poured over his urine.”
Its outward sense is that a small amount of impurity does not spoil a small amount of water, for it is clear that the place was purified with nothing more than that bucketful.
Likewise is the report of Abū Saʿīd al-Khudrī, recorded by Abū Dāwūd, who said:
“I heard the Messenger of Allah—peace and blessings be upon him—being told, ‘Water is drawn from the well of Budāʿah, a well into which the flesh of dogs, menstrual cloths, and other refuse are thrown.’ The Prophet—upon him be peace—replied, ‘Water is not rendered impure by anything.’”
The scholars endeavored to reconcile these ḥadīths, yet differed over the method, and their legal positions diverged accordingly. Those who took the Bedouin ḥadīth and the report of Abū Saʿīd at face value held that the two narrations of Abū Hurayrah are not to be interpreted rationally; compliance with them is an act of worship in itself, not because the water actually becomes impure.
The Literalists went further, asserting that even if someone were to pour urine into such water from a cup, it would still not be disliked to bathe or perform wuḍūʾ with it.
Others, who regarded a small quantity of water into which a slight impurity has fallen as merely disliked, reconciled the texts by interpreting the two ḥadīths of Abū Hurayrah as indicating reprehensibility, while taking the Bedouin narration and that of Abū Saʿīd in their literal, operative sense—that is, the water remains valid for purification.
Al-Shāfiʿī and Abū Ḥanīfah harmonized the two reports of Abū Hurayrah with the ḥadīth of Abū Saʿīd al-Khudrī by applying the former to a small quantity of water and the latter to a large body of water.
Al-Shāfiʿī further maintained that the criterion uniting the traditions is the measure mentioned in the ḥadīth of ʿAbdullāh ibn ʿUmar, related from his father and recorded by Abū Dāwūd and al-Tirmidhī—declared authentic by Abū Muḥammad Ibn Ḥazm—in which:
“The Messenger of Allah—peace and blessings be upon him—was asked about water frequented by wild beasts and livestock. He said, ‘If the water reaches two qullahs, it does not carry filth.’”
Abū Ḥanīfah, by contrast, set the threshold through analogy: he likened the spread of impurity through water to the spread of motion. When the body of water is such that it is deemed improbable for the impurity to permeate it entirely, the water remains pure.