to leasing it to him, he would have bid over his brother’s bid. If he offered more after the contract had been concluded, while rescission was still possible, he would be like someone who undercuts his brother’s sale. Both are forbidden by the explicit words of the Messenger of Allah—may Allah bless him and grant him peace—and this is the position of the four imams. How much more serious, then, is offering more when a valid lease is already in force! Such a bidder is disobedient, sinful and unjust, and deserves discretionary punishment. Whoever helps him in this has helped him in sin and transgression.

The tenant’s having his own commitment witnessed, without the landlord doing likewise, makes no difference here, for the contract does not require witnesses; it is valid without them. The trustee’s saying to him, “Have your commitment witnessed,” together with the tenant’s doing so, constitutes a lease valid according to Islamic law. Indeed, once the trustee has told him, “Have your commitment witnessed,” no one may offer more than he has.

The trustee must not lease the premises until he considers it most likely that no one will offer more. He must publicize their availability among prospective tenants who customarily rent such premises. Once he has done so, he has leased them at the going rate, and this is a lease valid according to Islamic law.

If, however, he favours one of his friends, someone who has done him a favour, or anyone else by leasing the premises below the going rate, he is acting unjustly and is liable for the shortfall in the rent due to the endowment’s beneficiaries.

If property rental rates change after a valid lease has been concluded, he has no right to rescind it on that account, for such fluctuations cannot be precisely controlled and fall outside what one can be required to account for. The value of the benefit derived from the property may vary over time rather than remain uniform. Thus, its value in winter