Does a shoe become pure by drying if the impurity on it has mixed with dust or become impure mud? And does impure mud or pebbles that stick to the shoe and detach from it after drying on the ground become pure? And does dust generally become pure by drying?

The bottom of the shoe is purified by rubbing it on the ground, and the impurity adhering to it falls off, making it permissible to pray in it. Similarly, the earth and the dust on it become pure through dryness. It is advised not to delve deeply or be overly meticulous in this matter to avoid falling into obsessive doubts (waswasah).