What is the legal basis for prohibiting combining a sale with certain stipulations?
Chapter on Selling Assets and Fruits
Al-Mughni
Book of Sales
Primary text
The justification for invalidating a sale due to a stipulation—as argued by those who disallowed conditional harvesting—is that stipulating work on property not yet owned, stipulating what the contract does not mandate, or stipulating delivery postponement are invalidating factors. However, the response is that the sale differs from lease because liability transfers upon delivery in sale, unlike lease, yet combining contracts of different natures is permissible, like combining the sale of a share of land (subject to pre-emption) and a sword (not subject to pre-emption).
Supporting text
The view that stipulating the seller's benefit invalidates the contract is countered by the ruling that a single stipulation is permissible, contrasting with the narration that the Prophet (peace be upon him) forbade 'sale and condition.' The correct understanding, as stated by Al-Tirmidhi, is that the prohibition is against 'two conditions in a sale,' implying that a single condition is permissible, which is what Ahmad adopted.