The ruling on one who rents a house and then buys it from its owner during the rental period

The questioner : As for selling it to the tenant, it may be said that a stronger ownership has come upon a weaker ownership, thereby invalidating it. Based on this, the original lessor is not entitled to anything of the rent, except if the sale contract was concluded upon it. And if we say that the lease is not annulled, then the one who bought it, having already rented it, pays the rent to the one who sold it to him. Is that clear?

The Shaykh : It was placed in a certain state, or in a state other than that. For example, he rented a house for ten thousand riyals, and during the term he bought it now. A sale contract has come upon this house, and a sale contract has come upon a lease contract. Which is stronger? The sale contract, because by it one owns both the benefit and the item itself. So do we say that because the stronger contract came upon the weaker, it invalidated it? In that case, the one who sold the house is not entitled to anything. Or do we say that this contract, which is the sale, came upon an item whose benefit had already been owned before the sale contract, so the lease is not invalidated? The school of thought holds that it is not invalidated, whether the buyer is the same tenant or someone else. Based on this, the one who leased it is entitled to the remainder of the rent.