Is it prohibited to enter into contracts other than sale (Bay')?
General Chapter
Al-Mughni
Book of Friday Prayer
Primary text
Contracts other than sale, such as leasing (Ijarah), settlement (Sulh), and marriage (Nikah), are not prohibited. The prohibition is specific to the contract of sale (Bay'). Other contracts do not equate to sale in their distraction from striving (Sa'i), due to their relative rarity, hence analogy to sale is invalid.
Supporting text
It is held by some that contracts other than sale, such as leasing, settlement, and marriage, are prohibited because they are contracts of exchange (Mu'awadah), resembling sale.