Does walking on the ground purify impurity, and is it obligatory to wash the places that I stepped on with my shoe, which was wet with what is suspected to be dung, three times, keeping in mind that I do not remember whether the dung touched the wet part of the shoe, and what must I do now?

It appears that the questioner is afflicted with waswasah (obsessive whispering). Therefore, it is advised to disregard these whisperings and pay no attention to them. As long as she is not certain about the impurity of what clung to her sandal, the original state is purity. Impurity is not judged except with certainty. Even if it were assumed to be impure, the transference of impurity is not judged except with certainty.

If the ground becomes impure, it is not obligatory to purify it except when intending to pray on it. Its purification is by pouring water over the impure spot. Many scholars are of the view that the earth, and whatever is permanently attached to it like a building, becomes pure by drying.