Ahmad ibn Muhammad ibn Isa, from Ahmad ibn Muhammad ibn Abi Nasr, who said: I mentioned to Abu al-Hasan al-Ridha عليه السلام, peace be upon him, about ‘the land-tax (kharaj) and what the people of his Household (Ahlul Bayt عليه السلام) followed concerning it.’ Imam عليه السلام said: “The tenth and half of the tenth are upon one who accepts Islam voluntarily. His land is left in his hand, and the tenth and half of the tenth are taken from him from what he cultivates of it. As for what he does not cultivate of it, the governor takes it and leases it to one who will cultivate it, and it belongs to the Muslims. And there is no zakat on anything less than five awsaq. And whatever is taken by the sword, that belongs to the Imam; he leases it according to what he sees fit, just as the Messenger of Allah سبحانه وتعالى, Allah's سبحانه وتعالى blessings be upon him and his family, did with Khaybar. The Prophet صلى الله عليه وعلى آله وسلم leased its land and its palm-trees. And the people say: ‘Leasing land and palm-trees is not valid when the uncultivated land (bayad) is greater than the cultivated land (sawad),’ yet Messenger of Allah سبحانه وتعالى, Allah's سبحانه وتعالى blessings be upon him and his family, leased Khaybar, and upon them in their shares is the tenth and half of the tenth.”