What is the ruling on the penalty clause agreed upon in a contract for the sale of a house, if the seller wishes to withdraw from the sale and agrees to pay this clause?

It is permissible for two parties to a sale to agree that whoever rescinds the sale pays a sum of money, unless there is a valid reason for rescission, such as the option of defect. This is because the original principle in a sale is its binding nature, and it should not be rescinded except by mutual consent of both parties. The Islamic Fiqh Academy has approved the permissibility of a penalty clause in all financial contracts except debts, based on the principle that "Muslims are bound by their conditions."

In the event that there was no prior agreement on penalizing the rescinder, and one party wishes to rescind without cause, the other party may request a sum. This falls under the category of annulment for more or less than the price, which is permissible according to the preponderant opinion of the scholars.