What is the ruling on istijmar (using stones or other dry materials to cleanse oneself after relieving oneself) after urinating for someone who had a wet dream and found traces of semen? Is water obligatory, or is istijmar sufficient despite the presence of the trace? And what about the practice of the Companions?

Semen is pure according to the Hanbalis and Shafi’is, but if it mixes with the impurity of urine, it becomes impure. Istijmar (cleaning with stones or similar dry material) is sufficient for it unless the impurity spreads beyond the usual place, in which case using water becomes necessary. The Maliki school of thought holds that water is necessary for removing semen in some cases. Istijmar is permissible, but it is preferable to combine istijmar with the use of water, by first using a stone to reduce the impurity and then using water.