I have a problem that I often fear I passed a small amount of urine during my prayer. This happens so often that I tend to store the clothes I fear may have the impurity on them in my room and not wash them until a few days later. Is this permissible, or is the fact that such a long interval passed between the time the urine came out and it being washed that even if I did wash the clothes thoroughly, it is too late as the urine would have already dried from days ago?
Note: please answer this as accurately as possible so that I can put my mind at ease.