the obligation to sell them at their fair market value. For this reason, he, peace and blessings be upon him, said:

“Leave people to trade, so that Allah may provide for some through others.”

The same applies when one co-owner sells to the other his share in something that cannot be divided: the co-owner needs the sale in order to receive his share, and the other suffers no harm. Likewise, the Prophet’s having a co-owner’s share valued when the other co-owner frees his own share of a slave: emancipation needs to be completed because partial emancipation causes harm, whereas selling his share either causes the seller no harm or causes harm outweighed by the need to complete the emancipation.

The same applies when another person has a right attached to someone’s property, as when someone owns legally protected improvements—plantings, a building or a well—on another person’s land. Examples include a purchaser when the share he purchased is taken by pre-emption; a seller to whom the item sold is returned because of a defect, when its price had been paid in real estate; and a borrower or tenant when the agreed term expires. If the owner does not remove these improvements, the landowner may purchase them at their value or allow them to remain in return for a fair market rent. Both arrangements involve an exchange: either for the improvements themselves or for the use of his land.

Likewise, compelling one co-owner to join the other in excavation or repair work is compelling him to enter into an exchange. Repair work entails purchasing materials and hiring workers, so this amounts to compelling him to purchase and hire. Since his co-owner needs this and the person making the contribution suffers no harm, he is obliged to enter into the exchange with him—sometimes to enable the property to be divided, and sometimes to preserve its joint ownership. Accordingly, if the Muslims need