He—may Allah have mercy on him—was asked:
A man was renting a nearby plot of land. While he was away travelling, someone bought the house adjoining the land he was renting, built it up, and incorporated it into his own house. What must be done?
He replied:
(*) He has no right to seize the rented land along with other property or incorporate it into his house. By doing so, he is an unjust usurper. The tenant may either terminate the lease on this account, in which case his obligation to pay rent lapses, or continue the lease and demand payment from the usurper for his use of the land.
He may also choose whether to leave the building on the land or have it taken down, if this falls within the terms of his lease. If it does not fall within those terms, he may not act with respect to the land without the owner’s permission. And Allah knows best.