What is the ruling of the Sharia on a dispute regarding the sale price of a share in a house, where a price was agreed upon ten years ago and a portion of it was paid, while the seller is now demanding today's value and the buyer considers the remaining amount a debt, with differing opinions on how to appraise the value (only by the amount paid, by the price of gold then and now, or by not recognizing banknotes)?

The sale with deferred payment until a time of ease (al-maysarah) is a matter of scholarly disagreement. The majority of scholars, including the Hanafis, Malikis, Shafi'is, and some Hanbalis, deem it invalid because the deferment period is unknown, leading to the corruption of the contract or the invalidation of the deferment period, thereby making the price immediately due.

However, some scholars, such as Ibn Hazm, some Hanbalis, and Ibn Uthaymeen, made an exception for this type of sale, based on the hadith of Aisha (may Allah be pleased with her) that the Prophet (peace be upon him) "sent to a Jew, 'Send me two garments until a time of ease (al-maysarah).'" They consider it valid and argue that a known deferment period is not a condition for it.

The majority of scholars responded to the reliance on Aisha's hadith by stating that it was merely a request and not a contract, and that the price becomes immediately due when an unknown deferment period is stipulated.

In the case of a corrupted contract made until a time of ease, the majority views its annulment as necessary. If part of the price was immediate and part deferred, the contract can be rectified for the immediate part and annulled for the deferred part; this is to achieve justice and prevent harm resulting from the difference in value, and is known as partial transaction validity.

As for a sale with a known deferred payment period, the seller is not entitled to demand an increase in price even if prices rise. The debtor is obligated to pay what is due from him at the time of incurring the debt. If he is in hardship, he should be given respite until a time of ease. If he is procrastinating despite being wealthy, then the procrastination of the rich is injustice.