Is there a threshold amount for the natural calamity loss to warrant a reduction in the purchase price of fruits?
Chapter on Selling Assets and Fruits
Al-Mughni
Book of Sales
Primary text
The apparent view in the Madhhab is that there is no difference between a small or large loss from calamity, except that a minor loss customary to occur, like a small, uncontrollable amount, is disregarded. Imam Ahmad stated that he does not consider the loss of ten or twenty fruits, but if the calamity is known, such as one-third (thuluth) or one-quarter, it should be accounted for. The prevailing view holds that destruction exceeding the usual small amount requires a reduction in the price proportionate to the loss. If all the fruit perishes, the contract is voided, and the buyer recovers the entire price.
Supporting text
There is another narration indicating that any loss less than one-third is the responsibility of the buyer, which is the opinion of Malik and Al-Shafi'i in his old view. This is because some fruit is naturally eaten by birds or scattered by the wind, making a fixed standard necessary. This standard is set at one-third because the Prophet, peace be upon him, indicated in matters of bequest that one-third is the limit of a large amount (thuluth wa thuluth kathir), implying it is the boundary of significant loss.