Section: If the lower floor belongs to one man and the upper floor to another, and the roof between them collapses, and one of them asks the other to rebuild it, but he refuses, is the refuser compelled to do so? There are two narrations, just as in the case of a wall between two houses. Al-Shafi'i has two opinions analogous to these two narrations. If the walls of the lower floor collapse and the owner of the upper floor demands that he restore them, there are two narrations: one of them is that he is compelled. This is the opinion of Malik, Abu Thawr, and one of the two opinions of al-Shafi'i. According to this narration, he is compelled to build it alone; because it is his property exclusively. The second is that he is not compelled. This is the opinion of Abu Hanifa. If the owner of the upper floor wishes to build it, he is not prevented from doing so, according to both narrations. If he builds it with his own materials, it remains as it was. If he builds it with materials from his own possession, it has been narrated from Ahmad: The owner of the lower floor may not benefit from it, meaning until he pays its value. It is possible that it means he may not inhabit it, which is the opinion of Abu Hanifa, because a house is built for habitation, so he does not own it like other things. It is also possible that he meant he may not benefit from the walls specifically—by placing timber, driving a nail, or opening a window—while he may still inhabit it without disposing of another person's property. This is the school of al-Shafi'i, because habitation is merely his presence within the courtyard of the walls without disposing of them, so it is similar to finding shade from them on the outside. As for if the owner of the lower floor demands the construction and the owner of the upper floor refuses, there are two narrations: one of them is that he is not compelled to build it nor to assist in it. This is the opinion of al-Shafi'i; because the wall is the property of the owner of the lower floor, peculiar to him, so no one else is compelled to build it or assist in it, just as if there were no upper floor upon it. The second is that he is compelled to assist him and build with him, which is the opinion of Abu al-Darda'; because it is a wall they both share in benefiting from, similar to a wall between two houses.

Section: If there is a wall between two houses belonging to one of them, and it collapses, and one of them asks the other to build it, or to assist in its construction, and he refuses, he is not compelled; because if the refuser is its owner, he is not compelled to build his own property that is peculiar to him, such as the wall of another person. And if the refuser is the other party, he is not compelled to build someone else's property, nor to assist in it. This does not result in a contradiction concerning the wall of the lower floor, where its owner is compelled to build it despite it being his exclusive property; because the apparent reality is that the owner of the upper floor owned it with a right to have it remain on the walls of the lower floor permanently, so the owner of the lower floor was obliged to enable him to exercise what he is entitled to, and the way to do so is through building; therefore it became mandatory, unlike our issue here. If the owner of the wall wishes to build it, or tear it down after building it, his neighbor cannot prevent him; because it is his property exclusively. If his neighbor wishes to build it, tear it down, or dispose of it, he has no right to do so; because he has no right over it.