Rather, stones should be used, or both methods combined. The well-known view, however, is that using water alone is preferable, even though it involves direct contact with impurity.

Regarding the use of carrion hides for dry substances, on the view that these hides are not pure, there are two positions reported from Ahmad. The sounder permits this; even if it is considered disliked, that disapproval is lifted when there is a need.

As for the objection, “This leads to contamination with smoke from impure substances,” this rests on the second principle: if an impure substance in a salt bed turns into salt, or undergoes a similar transformation, does it remain impure? Scholars hold two well-known views, both reported from Ahmad. He explicitly stated both positions regarding a pig roasted in an oven: does fire purify the matter adhering to the oven, or must the parts soiled by the pig be washed?

There are two explicitly recorded positions. The first is that the substance remains impure. This is the position of al-Shāfi‘ī and most of Ahmad’s followers, and one of the two views held by Mālik’s followers. Those who hold this view say that no impure substance is purified through transformation except wine that transforms of its own accord, and tanned hide—if tanning is understood as transforming the impurity rather than removing it.

The second view, which is the position of Abū Hanīfah and one of the two views held by the Mālikīs and others, is that it no longer remains impure. This is the correct view, for these substances are not covered by the scriptural prohibition, either in wording or meaning, nor are they analogous to what those texts prohibit