Imaam Abu Hanifah (rahimahullah) was once owed an amount of money by a certain fire worshipper. He thus went to the house of the fire worshipper to request payment. However, as Imaam Abu Hanifah (rahimahullah) arrived at the door of the fire worshipper, some najaasat (impurity) stuck to his sandal. Imaam Abu Hanifah (rahimahullah) shook the sandal to remove the impurity, and as the impurity was removed, it fell onto the wall of the fire worshipper’s home! Imaam Abu Hanifah (rahimahullah) was worried and perturbed. If he left the impurity on the wall, it would cause the wall to appear unsightly, and if he scraped it off, then some portion of the sand of the wall would also be removed.