buying firewood from the seller on the condition that he deliver it to a particular location, or buying a piece of cloth and stipulating that he tailor it.

Second: Invalid stipulations. This heading comprises several kinds:

1. A defective stipulation that nullifies the contract altogether. An example is for one party to make the sale contingent upon a second, unrelated contract, such as saying, “I sell you this item on condition that you lease me your house,” or, “I sell you this item on condition that you take me as a partner in that business of yours or in your home,” or, “I sell you this item for such-and-such an amount on condition that you lend me such-and-such a sum of dirhams.” Such a stipulation is invalid and voids the sale at its root, for the Prophet ﷺ forbade “two sales in one,” and Imām Aḥmad interpreted the ḥadith in precisely this way.

2. The second type of invalid stipulation in sales is one that is corrupt in itself yet does not cancel the sale, such as the buyer stipulating that if he incurs a loss on the commodity he may return it, or the seller stipulating that the buyer may not resell the item, and similar conditions. Such a stipulation is invalid because it contradicts the very nature of the contract, which gives the buyer unrestricted disposal over the purchased item. The Prophet ﷺ said, “Whoever lays down a condition that is not found in the Book of Allah, that condition is null and void, even if it be a hundred conditions,” agreed upon.