What is the ruling on the prayers of one who was ignorant of the obligation of purification (Istinja') before prayer and sufficed with wiping with the hand, and are his prayers valid despite the persistence of traces of impurity?

The question comprises several matters, detailed as follows:

1. Istijmar with the hand: Istijmar with the hand is deemed sufficient by some scholars if it thoroughly cleanses the area of impurity. 2. Ruling on Istijmar and water: Istijmar for defecation is sufficient, and water is not obligatory unless the faeces have spread beyond their original place. The best method for istinja' is to wipe the area with tissues and then wash it with water. Water becomes obligatory if urine spreads to affect most of the glans penis, or if faeces reach the buttocks. 3. Doubt about impurity affecting clothes: Doubt about impurity affecting clothes is not to be heeded, as the original state of clothes is purity. If the impurity is not known until after the prayer, then the prayer is valid, and it is recommended to repeat the prayer as long as its time remains.