What should one do who forgot whether he purified a ritually impure place, or who is not predominantly certain about the ritual purity or impurity of a specific place?

If you are afflicted by waswās (obsessive whispering), then ignore it and pay no attention to it.

However, if you are not afflicted by waswās and you doubt the purity or impurity of a place, then build upon the certain origin:

- If you are certain of the purity of a place and you doubt whether impurity has touched it, then its original state is purity. - If you are certain that impurity has touched it and you doubt whether you have removed it, then the place remains impure until you are sure of its purification; this is based on the juristic maxim: "Certainty is not removed by doubt."