Assalaamu alaykum. A bed sheet which had sexual impurity on it was kept aside for more than a month without being washing. Now the spots of impurity have retained their color and also some stiffness, even after a good laundry. Can it be considered as pure? I do not pray on it, but the problem is that my feet have cracked heels, which sometimes pull out tiny particles of fabric from clothes when in contact with them. In case it is considered impure, is it obligatory for me to always take precautions so that my or someone else's cracked heels do not get in contact with the place of impurity and get impure particles of fabric stuck in their heels? Please clarify this matter. May Allah reward you.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.

It is obvious that you are overwhelmed by Waswaas (obsessive whisperings), therefore, our advice to you is to repel such Waswaas and to pay absolutely no attention to it.

If this bed sheet is stained with impurity, it is sufficient to purify it by pouring some water over it that is greater in quantity than the impurity (to make sure that it is most likely removed). If you do that, then the bed sheet is ruled to be purified and there is no harm to touch it or sit on it, regardless of whether it is wet or dry.

You should know that whenever you have doubts about the purity of any object, the basic principle is that it is pure. You should always act upon this basic principle until you know with certainty that the case is otherwise.

Moreover, the insignificant amount of impurity is excused and pardoned according to many scholars. If what stained the bed sheet was semen, then you should know that semen is pure according to the preponderant view of the scholars. Therefore, there is no need for the question to begin with.

Lastly, we repeat that you should repel and disregard such obsessive doubts, as getting carried away with them leads to grave evils.

Allah knows best.