Prayer: Bed Sheets and Quilts for Those Praying Lying Down
Practical Laws of Islam as per the teachings of Ayatullah Sistani
Ruling 833
With regard to the bed sheet or quilt that is used by someone who must perform prayers while lying down, it is not necessary for it to fulfil the conditions of clothing of someone performing prayers unless it is used in such a way that it can be said to be worn, like if he were to wrap himself in it.