Muhammad ibn al-Hasan al-Saffar, from Ya'qub ibn Yazid, from Ahmad ibn Muhammad ibn Abi Nasr, who said: I (narrator) asked Abu al-Hasan عليه السلام, peace be upon him, about ‘what the mine brings out, whether little or much. Is there anything due in it?’ Imam عليه السلام said: "There is nothing due in it until it reaches the amount in which zakat would be due in its like: (which is) twenty dinars."