What is the ruling on the seller stipulating the right to reclaim the sold land when he is able to pay its price, with the possibility of its price increasing over an indefinite period, and what if this period is specified in the contract?

This contract is void due to the condition of rescinding the sale upon ability [to repay], and because it involves an attempt to legitimize usury, which is the intent to give money for a term, with the land's benefit being unlawful profit. It is stated in the Mudawwanah that buying a slave girl with the condition that the seller has the right to her back whenever he brings the price is impermissible. This sale is void whether they specify a duration for the rescission or restrict it. The contract would be permissible if they agreed before the sale and then concluded the contract without a fulfillment condition.