If an impurity touches a limb of ablution after it has been washed during ablution, is it obligatory to rewash that limb immediately before completing the ablution, or can one complete the ablution and then remove the impurity later? Does this invalidate the ablution? Does washing the limb that became impure affect the condition of continuity if the limb before it has dried? And are the ablution and prayer considered valid in case of doubt about the foot becoming impure after washing it and the presence of a questionable odor?

The cure for intrusive thoughts (waswas) is to ignore them and pay them no mind. Although bathroom cockroaches are impure, the impurity does not transfer merely by placing one's foot on the spot where the cockroach was killed, unless there is absolute certainty, and the default state is purity. It is not necessary for the organs of ablution to be free from impurity for the ablution to be valid. So, if someone performs ablution and there is an impurity on one of their limbs, and they intend, by washing it, to remove the ritual impurity, it is sufficient. Re-washing the right foot does not invalidate the sequence (muwalah) in ablution if the interval is short.