What is the ruling on using banknotes and coins whose manufacturing material is unknown, such as the five-pound note that contains beef fat? And does purchasing halal items with it make the money earned from the work permissible or forbidden? And what is the ruling on credit cards that may contain forbidden materials?

There is no objection to using paper currency, metallic coins, and credit cards that adhere to Sharia (definition)-compliant regulations. No attention should be paid to the materials from which they are made, even if they contain forbidden or impure substances, because these materials are chemically treated and transformed into another substance. This transformation (istihalah) necessitates purity and permissibility.

Istihalah is the change in the true nature of an impure or forbidden substance, and the transformation of its essence into a substance distinct from it in name, characteristics, and properties. Examples include: the purification of wine through istihalah, and the permissibility of milk and meat from an animal that was fed impurities then confined and fed pure substances, as well as crops and fruits that were watered with impure water and then with pure water.

The Islamic Organization for Medical Sciences has determined that istihalah transforms impure substances into pure ones, and forbidden substances into permissible ones according to Sharia. Examples include: gelatin formed from the istihalah of the bone of an impure animal, soap produced from the istihalah of pig fat, and cheese made with rennet from a dead animal whose meat is permissible to eat. As for ointments and creams that contain pig fat, their use is not permissible unless istihalah has occurred in them.