Can impure earth be purified by the sun, wind, or natural drying?
Chapter on Praying with Impurity and Other Matters
Al-Mughni
Book of Prayer
Primary text
Impure earth is not purified by the sun, the wind, or mere desiccation. This is the position of Abu Thawr, Ibn al-Mundhir, and Al-Shafi'i according to one of his two opinions. The proof for this is the command of the Prophet (peace be upon him): 'Pour a bucket of water over his urine.' This command implies obligation. Furthermore, it is impure matter, and it cannot be purified without washing, like garments.
Supporting text
Abu Hanifa and Muhammad ibn al-Hasan hold that it is purified when the trace of the impurity vanishes. Abu Qilabah stated that the drying of the earth is its purification, citing the narration that dogs would urinate, pass, and turn around in the mosque, yet they would not sprinkle anything there. However, the hadith narrated by Ibn Umar, as reported by Al-Bukhari, does not mention urine specifically; it may mean their movement occurred after the urine had already been present.