He—may Allah have mercy on him—was asked about a man who had erected a building and projecting structures above the entrance to the upper storeys, overlooking his neighbour’s private quarters. He had also obstructed his neighbour’s stairway entrance so that he could neither carry a tray of dough down nor bring a water carrier’s waterskin up.

He answered:

A neighbour may not add anything to a shared passage that has no outlet without the consent of his fellow user or the other co-owners. Nor may he make alterations to his own property that harm his neighbour. If he does so, the co-owner is entitled to have the source of the harm removed, whether before or after the sale. However, if it is removed before the sale, it may not be reinstated; if it is removed after the sale, the purchaser is entitled to rescind the sale because of this diminution.

He was also asked:

A man purchased some shops, including their land and buildings, twenty years ago. Above them is an upper storey. Someone then appeared claiming ownership of that upper storey, but the owner of the shops did not acknowledge the validity of his claim. The claimant erected a new structure on the upper storey. Is he obliged to