He answered:

If this harms the neighbour—for example, by allowing him to overlook the neighbour’s property—he must provide a barrier preventing him from overlooking the property below. If it causes the neighbour no harm, either because he builds a barrier preventing such overlooking or because the building does not overlook the neighbour’s property in the first place, he may not be prevented from building.

He was asked:

A man purchased a house overlooking a public thoroughfare and then wished to extend it. He purchased a specified number of cubits of land along the side of the thoroughfare from the representative of the public treasury and erected a wall on the land he had purchased. He also wished to erect a structure spanning the Muslims’ thoroughfare so that he could build a house upon it. Is this permissible or not? Is the sale of the land purchased from the representative of the public treasury, which forms part of the Muslims’ thoroughfare, valid or not? Is the witness who testifies that it belongs to the public treasury guilty of sinful conduct or not? If the second man claims that his building has caused the Muslims no harm, is his claim to be entertained? What constitutes the harm on account of which building over the thoroughfare is prohibited? May a Muslim judge permit him to proceed in the manner described, or not?

He answered:

Praise be to Allah. It is not permissible to sell any part of the Muslims’ public through-road, nor does the representative of the public treasury have the authority to sell it, whether the road is wide or