Musnad Ahmad 30:3353

'Ali narrated to us, from al-Hadhdha', from Ibn Sirin, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "The animal (al-'ajma') is [a cause of] liability-free loss (jubar), and the mine is [a cause of] liability-free loss (jubar), and in the buried treasure (al-rikaz) is one-fifth."