The rulings of both differ, for the right of pre-emption (shuf'a) is established in a share of property (shiqs) but not in a sword, and yet it is permissible to combine them. Al-Khiraqi's statement that the contract is void here may be specific to this issue and its likes, where the condition leads to dispute; for the seller might want to cut it from the top so that a remainder is left for him, while the buyer wants to extract it completely to increase what he takes, thus leading to dispute, which is a corruption (mafsada), so the sale becomes void because of it. It is also possible that what resembles it should be compared to it, regarding the stipulation of a benefit for the seller in the sold item, for the reasons we mentioned at the beginning of the issue. The former is more appropriate for two reasons: First, he said elsewhere: "The sale is not void due to a single condition." Second, the madhhab holds that it is correct to stipulate a benefit for the seller in the sold item, such as buying a garment and stipulating upon its seller that he sew it into a shirt, or a piece of hump fat (fil'a), or stipulating that he make it into a sandal, or a bundle of firewood (jurza), and stipulating its transport to a known location. Ahmad explicitly stated this in a narration by Muhanna and others. So much so that al-Qadi said: "I did not find a narration in support of what al-Khiraqi said regarding its invalidity." Ahmad argued that Muhammad ibn Maslama bought a bundle of firewood from a Nabataean and stipulated that he carry it. Ishaq and Abu 'Ubayd also held this view. Abu Hanifa said: It is permissible to buy a piece of hump fat and stipulate upon the seller that he attach a strap (tashrik) to it. It was narrated from Ibn Abi Thawr and al-Thawri that they invalidated the contract with this condition because it is a corrupt condition, so it resembles other corrupt conditions. It was narrated from the Prophet (may Allah bless him and grant him peace) that he forbade a sale and a condition. As for us, we have what preceded, and it is not established that the Prophet (may Allah bless him and grant him peace) forbade a sale and a condition. Rather, it is correct that the Prophet (may Allah bless him and grant him peace) forbade two conditions in one sale, as narrated by al-Tirmidhi. This implies by its concept the permissibility of a single condition. Ahmad said: The prohibition is only against two conditions in one sale, but as for a single condition, there is no harm in it.