What is the ruling regarding impurity on the sole of the shoe or boot after rubbing it on the ground until the essence of the impurity is removed?
Chapter on Praying with Impurity and Other Matters
Al-Mughni
Book of Prayer
Primary text
There are three narrations regarding impurity on the sole of the shoe or boot after rubbing it on the ground until the essence is gone. The primary ruling states that rubbing it on the earth suffices, and prayer therein is permissible. This is the view of al-Awza'i and Ishaq. The evidence is the Hadith transmitted by Abu Dawud from Abu Hurayrah stating, 'If one of you treads upon filth with his shoes, their purification is the dust.' Similar reports come from Aisha and Abu Sa'id. Furthermore, the companions used to pray in their shoes, which necessarily incurred various impurities, implying that friction purified them, otherwise, prayer would be invalid.
Supporting text
A second narration requires washing the shoe like all other impurities, arguing that rubbing does not remove all parts of the impurity. A third narration mandates washing only if the impurity is urine or feces due to their severity, but not for other impurities. Furthermore, some scholars hold that rubbing suffices only after the impurity has dried, as residual wetness cannot be pardoned, contrary to the apparent meaning of the narrations which do not differentiate between wet and dry.