Prayer: Obligation and Hardship in Procuring Clothing
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 829
If a person does not have anything with which he can cover his private parts in prayers, it is obligatory for him to procure such a thing even if he has to hire or purchase it. However, if procuring it would cause him excessive difficulty due to his poor financial situation, or the item being expensive, or him suffering some injustice, then it is not necessary for him to procure it and he can perform prayers according to the instructions that were mentioned regarding a naked person.