has made earth a means of purifying the soles of sandals and the hems of garments, and has called it a purifier, then it is all the more fitting that it should purify itself. Thus, when an impurity is transformed within the earth and becomes earth, it is no longer impure.

The scholars have also disagreed about cases in which the essential nature of an impurity is transformed. They agree that wine becomes pure if, by Allah’s action and without its owner intending it, it turns into vinegar. When its owner deliberately turns it into vinegar, however, they disagree and draw various distinctions. The correct view is that, if he deliberately turns it into vinegar, it does not become pure under any circumstances, as is established from ʿUmar ibn al-Khattāb—may Allah be pleased with him. This is because the Prophet’s prohibition of turning wine into vinegar is authentically established, and because keeping it is a sin, whereas purity is a blessing, and sin cannot be a cause of blessing.

They have also disagreed about an impurity that becomes salt in a saltworks, turns into ash, or—as with carrion, blood, and pus—becomes earth, such as the soil of a graveyard. There are two views on this within the schools of Mālik and Ahmad. The first is that it is pure, which is also the position of Abū Hanīfah and the Zāhirīs. The second is that it is impure, which is the position of al-Shāfiʿī.

The correct view is that all of this is pure if no trace of the impurity remains—neither its taste, its colour, nor its smell. For Allah has permitted wholesome things and forbidden foul things, and this depends on the properties and essential natures of the substances themselves.