Does dry najasah transfer from the mouse to the rug, and from there to the garment, and likewise from the sandal to the foot, knowing that this is [a matter of] waswasah and [mere] expectations?

The cure for obsessive whispers (waswas) is to ignore them and pay them no mind. So, no matter how much Satan whispers about the impurity of a place or thing, do not pay attention to it and build upon the original state, which is the persistence of purity. Impurity does not transfer from a dry place to another dry place. If you doubt the impurity of footwear, rule by its original purity. A small amount of impurity is absolutely excused by some scholars. Cast these whispers away, and there is no harm in acting upon the strong presumption (ghalabat al-dhann) that the impurity has been removed. Always maintain the original state, which is purity.