The World Federation One Stop Fiqh

Ruling 802

The second condition: based on obligatory precaution, the clothing with which a person performing prayers covers his private parts must be permissible (mubāḥ) [i.e. it must not be usurped (ghaṣbī)]. If a person knows that wearing usurped clothing is unlawful or he does not know the ruling due to his negligence, and he intentionally performs prayers with that clothing, then based on obligatory precaution his prayers are invalid. However, with regard to usurped things that do not on their own cover the private parts, and things that the person performing prayers is not currently wearing – such as a big handkerchief or a loincloth in his pocket, even though they could cover his private parts – and things that he is currently wearing but under which he has some other clothes that are not usurped and which cover his private parts, in all of these cases, the fact that these things are usurped do not affect the validity of the prayer, although as a recommended precaution using such things should be avoided.