Musnad Abu Ya'la al-Mawsili 155:210

Hadaba narrated to us, Hammad bin al-Ja'd narrated to us, Qatada narrated to us that Muhammad bin Sirin narrated to him that Abu Hurairah narrated to him that the Prophet, peace and blessings of Allah be upon him, decreed that the animal (al-'ajma') is [a cause of] immunity [from liability], and the mine is [a cause of] immunity [from liability], and the well is [a cause of] immunity [from liability]. And in the buried treasure (al-rikaz), there is one-fifth.