899 - Issue: He said: (Whoever leases a property, it is permissible for him to have someone else reside in it if they take his place.)

The summary of this is that whoever leases a property for residential purposes may reside in it, and may allow anyone he wishes to reside in it who takes his place in terms of harm, or is even less harmful. He may place in it what a resident would customarily have, such as baggage and food, and he may store in it clothing and other items that do not cause it harm. He may not allow anyone who would cause it harm to reside in it, such as fullers and blacksmiths, because that causes damage to it. He may not keep livestock in it, because they defecate therein and spoil it. He may not place dung in it, nor a hand-mill, nor anything that would damage it. It is not permissible to place anything heavy on a ceiling because it puts a burden on it and breaks its wood. He may not place in it anything that would cause it damage, unless he stipulates that. This is the opinion of al-Shafi'i and the scholars of rational deduction (Ahl al-Ra'y). We know of no dissenter regarding this. This is so because he has the right to utilize the contracted object himself or through his deputy, and the one who resides in it is a deputy for him in utilizing the contracted object; therefore, it is permissible, just as if he appointed an agent to take possession of a sold item or a debt owed to him. He does not have the right to do what would harm it, because that exceeds what was contracted; therefore, he has no right to do so, just as if he purchased something, he does not have the right to take more than it. As for making the house a storage space for food, our companions have said: This is permissible, because it is permissible for him to make it a storage space for something else. It is also possible that it is not permissible, because that leads to the fire of cooking potentially affecting its floor and walls, which is a harm that the owner of the house would not consent to.

Section: If one leases a house, it is permissible to make the contract absolute without needing to mention the residence or its description. This is the opinion of al-Shafi'i and the scholars of rational deduction. Abu Thawr said: It is not permissible until he says: 'I will spend the night in it with my family,' because residential needs vary. If he leased it for him to reside in, and then he married a woman, he would not have the right to have her reside with him. Our position is that a house is only leased for residence, so it is unnecessary to state it, similar to an absolute price in a land where a known currency is used [in it, and the variation in residence is slight, so there is no need to define it]. What he mentioned is not correct, for the harm hardly varies by the number of those who reside [in it] and their fewness, and it is not possible to define that. Therefore, reliance upon customary usage (urf) suffices in this matter, just as in entering a bathhouse and the like. If he were to stipulate what he mentioned, it would be obligatory for him to state the number of residents, and that no guest, visitor, or anyone other than those he mentioned should spend the night with him, and he would have to know the description of the resident, just as he knows that when he leases for the purpose of riding.