A third example: A man ties a rope to a large stone contaminated with impurity, and ties the rope to his hand or around his waist. His prayer is valid, because the large stone is not dragged along when he walks.
A fourth example: A man ties a rope to a small impure stone, and ties the rope to his hand or around his waist. His prayer is invalid, because it is dragged along when he walks; thus, it follows him, making him like one who carries impurity. This may be posed as a riddle: a man is connected to a great and substantial impurity, yet we say that his prayer is valid; while another man is connected to a small and slight impurity, yet we say that his prayer is invalid.
This is the view adopted by the author, may Allah have mercy on him.
The correct view, however, is that the prayer is not invalidated in either case, because the impurity has not come into direct contact with his garment, which constitutes his covering in prayer, nor with the place where he prays, nor with his body. Need may require this, especially in earlier times: a person might be out in the open with a small dog and fear that, if he lets it go, it will run away and not return. With no tree nearby to which he can tie it, he holds it in his hand and prays. What, then, could invalidate his prayer?!
As for their saying that the impurity follows him, we reply: in reality it is separate from him, and there is a barrier between him and it—namely, this rope.
“Whoever sees impurity upon himself after his prayer, and does not know whether it was present during it, need not repeat the prayer. But if he knows that it was present during it, yet forgot it or was unaware of it, he must repeat the prayer.”
His statement, “Whoever sees impurity upon himself after his prayer, and does not know whether it was present during it, need not repeat the prayer. But if he knows that it was present during it, yet forgot it or was unaware of it, he must repeat the prayer,” refers to impurity that is not excused, for the presence of an excused amount of impurity does not affect the prayer.