Definition and the Ruling of Istiḥālah
Issue No.212- If an original najāsah undergoes such a change that it takes on a new name and is no longer called by its previous name, it will become ṭāhir. Such a change is called “istiḥālah” (transformation) such as a dead dog in a salt-marsh that transforms into salt. In addition, when a najis object changes completely, for example, if najis wood burns down into ashes, or najis water changes into vapour, it becomes ṭāhir. However, if only the shape is changed like najis wheat that is made flour, it does not become ṭāhir.
