Musannaf Ibn Abi Shayba 28:178

Mu'tamir ibn Sulayman narrated to us, from 'Umar al-Dabbi, who said: While some men were cursing each other and turning over—or stirring up—the earth, they struck a treasure. Muhammad ibn Jabir al-Rasibi was over them, so he wrote to 'Adi regarding it. 'Adi wrote to 'Umar ibn 'Abd al-'Aziz, and 'Umar wrote: "Take the fifth from them."