What is the ruling on doubting the emission of pre-seminal fluid (madhy) after performing ablution (wudu)? And what is the ruling if one is certain of its emission during prayer? And how is clothing purified if it is stained with some of the pre-seminal fluid?

Doubt about the occurrence of an invalidator of ablution after it—whether it be madhiy (pre-seminal fluid) or something else—does not invalidate the ablution. This is because the original state is the persistence of purity, and it is not removed by doubt. However, if a person ascertains that madhiy has exited, then the ablution is invalid, and likewise the prayer if that occurred before it or during it.