Is the water remaining in the vaginal opening after answering the call of nature, or that which exits after ablution and prayer, impure and does it invalidate the prayer?

The water remaining on the limb after istinja' (washing after defecation or urination) is pure because it has separated from the impurity after its removal. As for the moisture found on the clothes, it appears to be the residue of the istinja' water, which is pure. There is no need for these doubts and whispers [from Satan], and the default is the validity of the prayer unless there is absolute certainty that something exited before or during ablution that necessitates repeating it.