As for replacing its building with another, Umar and Uthmān rebuilt the Prophet’s mosque—may Allah bless him and grant him peace—with a structure different from the original, and enlarged it. The same applies to the Sacred Mosque. It is established in the two Sahīh collections that the Prophet, may Allah bless him and grant him peace, said to Āishah:

“Were it not that your people have only recently emerged from the age of ignorance, I would have demolished the Kaaba, rebuilt it at ground level, and given it two doors: one through which people would enter and another through which they would leave.”

Thus, were it not for an overriding consideration, the Prophet, may Allah bless him and grant him peace, would have altered the Kaaba’s structure. It is therefore permissible to change the form of an endowed building to secure a greater benefit.

As for replacing one plot of land with another, Ahmad and other scholars explicitly permitted this, following the Companions of Allah’s Messenger, may Allah bless him and grant him peace. Umar did this, and the matter became widely known without anyone objecting.

As for replacing property endowed to generate income with something better—for example, when someone endows a house, shop, orchard, or village that yields little income, then replaces it with something more beneficial to the endowment—Abū Thawr and other scholars permitted this. Among them was Abū Ubayd ibn Harbawayh, the judge of Egypt, who also ruled accordingly. This follows by analogy from Ahmad’s ruling permitting a mosque to be moved from one site to another for a beneficial purpose. Indeed, if it is permissible, for the sake of a benefit, to replace a mosque with something that is not a mosque, so that its former site becomes a market, then replacing one income-producing property with another is even more clearly permissible. This also follows by analogy from his ruling permitting a sacrificial offering to be replaced with a better one.

He also explicitly ruled that if a mosque stands at ground level and people wish to raise it and build a water-supply facility beneath it, and the neighbours prefer this, it should be done. Some of his followers, however, prohibited replacing a mosque, a sacrificial offering, or endowed land. This is also the position of al-Shāfiī and others. Nevertheless, the scriptural texts, transmitted reports, and analogical reasoning entail that replacement is permissible to secure a benefit. And Allah, glorified and exalted is He, knows best.