What is the ruling concerning prayers that were performed while unaware of the presence of impurity on the body; must they be repeated or are they waived?

The removal of impurity is not a condition for the validity of wudu' (ablution) if it is not on the two private parts (front and back). As for impurity emerging from the two private parts and present on them, its removal is a condition for the validity of wudu' according to the Hanbalis. However, the more correct narration and the view of the majority of scholars is that wudu' is valid before performing istinja' (washing after defecating or urinating). The impurity of alcohol does not emerge from the two private parts, so it does not affect the validity of wudu'. Based on this, the impurity of madhy (pre-seminal fluid) or alcohol does not invalidate wudu' and does not necessitate repeating prayers.