Answered by Shaykh Faraz Rabbani
Is it allowed to place a plastic mat over the bed to avoid soiling of bed sheet?What if some mazi oozes out and soils the clothes one is wearing, and these clothes then come in contact with bed sheet or a cloth covering the couple?Will the bed sheet or covering cloth be najas or not?This is specially important in winters when blankets and quilts are used that are not easy to wash?
Walaikum assalam wa rahmatullah,
There is no reason why placing such a sheet would be impermissible. However, it is not necessary and could well be excessive. One is only responsible to remove ritual filth that one knows of or sees. Also, it is not necessary to wash away filth from bed sheets and the like immediately; rather, one can do so when one is changing the bed sheets. And one filth has dried, it is not considered to transfer upon contact with one’s body or clothes unless traces of the actual filth appear on them.
And Allah alone gives success.
Faraz Rabbani