neither stones nor water can be found, then anything that removes the impurity—whether it be a mineral from the earth or some other substance—may take their place, with the exception of bone, dung, and anything permissible to eat; it is not allowed to use such items for istinjāʾ (ritual cleansing).

It is disliked to cleanse oneself with charcoal, and no one may perform istinjāʾ with his right hand. Whoever prays without first performing this cleansing must repeat the prayer; Mālik said that the repetition is required as long as the prayer’s time has not yet elapsed.

Stones purify only the orifice itself and whatever impurity is inside or directly upon it. Once the filth spreads beyond that area, it is treated like any other part of the body, and only water can remove it.

Using stones for istijmār (wiping with solids) is permissible whether one is at home or on a journey, and whether or not water is available. No istinjāʾ is required for the mere emission of wind.