Is it valid to mortgage property that cannot be sold?
General Chapter
Al-Mughni
Book of Pledges (Collateral)
Primary text
The mortgage (*rahn*) of an item that is not valid for sale is invalid. This includes a female slave who has borne a child to her master (*umm walad*), an endowed property (*waqf*), or an already mortgaged item. The ruling is based on the purpose of the mortgage being securing the debt via its price upon sale, which is impossible for such items. Abu Hanifa and Muhammad hold this view, which is one opinion of Al-Shafi'i.
Supporting text
Malik, Abu Yusuf, Abu Thur, Al-Muzani, and Ibn Al-Mundhir permit mortgaging an item for an increased debt, arguing that if a new mortgage were added, it would be permissible, thus increasing the debt secured by the original mortgage should also be permissible. They further analogize this to ransoming an injuring slave where the slave becomes collateral for both the original debt and the ransom amount.