Is it sufficient to pour water over the area affected by urine spray without wiping it, and why is wiping not sufficient as it is in istinjāʾ, and are the previous prayers invalid?

Purifying a body part or garment stained with urine is done by flowing water over it, not merely by wiping it, as wiping is not considered washing. As for istinja (definition)' (cleaning oneself after defecating or urinating), it is permissible to wipe with a stone or similar object to remove impurities, and water is not a condition, as a facilitation and to remove hardship due to the frequent need to relieve oneself and the scarcity of water sometimes. This concession is specific only to the area where the impurity exits and does not extend to the rest of the body or garment. What goes beyond the usual area must be washed with water.