Is it permissible to wipe a baby girl's thighs with a single wet wipe after changing her diaper to cleanse them from urine, and is what splatters on her thighs considered a small amount of impurity that is overlooked? What is the treatment for obsessive-compulsive disorder (OCD) regarding impurity? Is pre-seminal fluid (madhy) considered a small amount of impurity that is overlooked, and does a small amount of impurity transfer if it touches something wet?

Certainty is not dispelled by doubt, and a ruling of impurity on something is only made with certainty of the impurity's transfer to it. So, if you doubt the transfer of impurity, do not pay attention to the doubt, and act upon the original principle, which is the persistence of purity. Some scholars have held that if a wet pure object meets a dry impure object, or vice-versa, the impurity does not transfer. They also held that if urine dries, the ruling of impurity does not transfer to what it touches, whether wet or moist. Sheikh Al-Islam held that a small amount of impurity is always excused. There is no harm for a person afflicted with obsessive doubts to act upon any of these opinions. The ruling is that whatever is excused among impurities remains excused even if it transfers to what it touches. It is not obligatory to wash the bedding after intercourse except for the specific spot that you are certain was affected by impurity. Discard illusions and do not yield to obsessive whispers. Whenever you have doubt about something becoming impure or the transfer of impurity, build upon the original principle, which is purity.