Is an agreement invalid if the agreed wages for transporting a letter depend on the time of delivery?
General Chapter
Al-Mughni
Book of Leasing
Primary text
An agreement to hire a person to carry a letter where the wages are fixed at twenty if delivered by a specific day, and reduced to ten if delivered one day later, is invalid (fasid). The carrier is only entitled to the customary wage for similar services (ajr mithl). This situation is analogous to the preceding issue concerning conditional rent based on destinations.
Supporting text
A contrasting narration attributed to Abdullah concerning hiring a beast of burden, where the rent is ten if returned the next day and five if returned today, indicates that this specific arrangement is permissible ('no harm'). This specific narration suggests the validity of the lease contract, contrary to the general apparent view of Ahmad regarding similar conditional agreements.