An Nasai: Hadith 5734

"I asked Rafi' bin Khadij about leasing land in return for Dinars and silver. He said: 'There is nothing wrong with that. During the time of the Messenger of Allah they used to rent land to one another in return for what grew on the banks of streams and where the springs emerged - some areas of which might give good produce and some might give none at all - and the people did not lease land in any other way. So that was forbidden. But as for leases where the return is known and guaranteed, there is nothing wrong with that.'"