What is the ruling on the buyer stipulating a discount of a sum of money for each day of delay in handing over the house, after the seller had accepted the first condition, which was delivery within a year, but failed to fulfill it?

It is permissible for the buyer to stipulate a penalty clause against the seller for delaying the delivery of the sold item, provided it is within the bounds of the damage incurred by the buyer due to this delay. It is permissible to stipulate a penalty clause in all financial contracts except for those where the obligation is a debt. This includes contracting and manufacturing (istisna') agreements. There is no objection to obligating the seller to pay a fine equivalent to the actual damage, whether the clause is associated with the contract or in a subsequent agreement if agreed upon. Actual financial damage includes real loss and certain lost profit, but does not include moral or emotional damage.