“If the water reaches two qullahs, it does not retain impurity” (1).
They cited as evidence for distinguishing between human urine and other impurities the Prophet’s saying: “None of you should urinate in standing water that does not flow, then bathe in it” (2). Thus, the Prophet ﷺ prohibited urinating and then bathing in it. This is general in meaning; however, an exception is made for water whose removal would be burdensome, on account of the hardship involved.
The second view—adopted by the later authorities of the school—is that there is no distinction between human urine and liquid human excrement, on the one hand, and other impurities, on the other: all are alike (3). Thus, if the water reaches two qullahs, it does not become impure unless its properties change; but if it is less than two qullahs, it becomes impure merely through contact.
The third view—chosen by Shaykh al-Islam (4) and a group of scholars—is that
(1) Reported by Ahmad, 2:12, 27; Abu Dawud, Book of Purification, chapter: What Defiles Water, no. 63; al-Tirmidhi, Chapters on Purification, chapter: What Has Been Reported That Nothing Defiles Water, no. 67; and Ibn Majah, Book of Purification, chapter: The Amount of Water That Is Not Defiled, no. 517, on the authority of Ibn Umar. It was graded weak by Ibn Abd al-Barr and Ismail al-Qadi. It was authenticated by a number of scholars, including Ahmad, al-Shafii, Ibn Main, Ibn Mandah, Abd al-Haqq al-Ishbili, Ibn al-Mulaqqin, and others. Al-Nawawi said: “It is authentic; the hadith masters authenticated it.” Al-Khulasah, no. 9. Ibn Taymiyyah said: “Most scholars of hadith hold that it is a hasan (sound) hadith and may be used as evidence.” See al-Ahkam al-Wusta, 1:154; Majmu al-Fatawa, 21:41; al-Talkhis al-Habir, no. 4; and Tahdhib al-Sunan by Ibn al-Qayyim, 1:56.
(2) Reported by al-Bukhari, Book of Ablution, chapter: Urinating in Standing Water, no. 239; and Muslim, Book of Purification, chapter: The Prohibition of Urinating in Stagnant Water, no. 282, on the authority of Abu Hurayrah.
(3) See Sharh Muntaha al-Iradat, 1:18.
(4) See Majmu al-Fatawa, 21:32; and al-Ikhtiyarat, p. 4.