Prayer: Ignorance of the Ruling on Praying with Usurped Clothing
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 803
If someone knows that wearing usurped clothing is unlawful but does not know the ruling on performing prayers with it, and he intentionally performs prayers with usurped clothing, then as per the details mentioned in the previous ruling his prayers are invalid based on obligatory precaution.