If the cost price in a murabaha sale is later discovered to be different than what was stated, what is the ruling?
Chapter on Selling the Musarrah (Animal with milk retained in udder)
Al-Mughni
Book of Sales
Primary text
If it becomes known, through notification or admission, that the cost price was less than stated (e.g., ninety when one hundred was declared), the sale remains valid. This difference is treated as an increase in the price. The buyer has the right to recover the excess paid, which is the difference in the cost price (ten dirhams), thereby reducing the profit margin by that amount (to nine dirhams profit for a total price of ninety-nine). This view is held by Al-Thawri and Ibn Abi Layla.
Supporting text
Abu Hanifa holds that the seller has the option between taking the full stated price or voiding the sale, analogous to a sale involving a defect. The buyer has the option, according to a narration from Ahmad, to take the item at the actual cost plus its proportionate profit, or to reject the sale, as the buyer might have relied on the specific stated price for external reasons. However, the apparent view is that the buyer has no option because they have received something better than what they might have based their final agreed price upon.