The World Federation One Stop Fiqh

Ruling 807

If a person purchases clothing with money on which the one-fifth tax (khums) has not been paid, and the purchase is a non-specified undertaking (al‐kullī fī al‐dhimmah),18 as most purchases are, the clothing is lawful (ḥalāl) for him and he owes khums on the money he paid for the clothing. However, if a person purchases clothing with the actual money on which khums has not been paid,19 then performing prayers with that clothing without the authorisation of a fully qualified jurist (al‐ḥākim al‐sharʿī) is ruled as being the same as performing prayers with usurped clothing.

18 This refers to a purchase in which the actual thing with which the payment is made is not specified. For example, a buyer purchases some goods for £20 without specifying to the seller that he is purchasing the goods with a particular £20 note.