Musnad Ahmad 30:710

Muhammad ibn Bakr narrated to us, Ibn Jurayj informed us, Ibn Shihab informed me, from Sa'id ibn al-Musayyib and Abu Salamah ibn 'Abd al-Rahman ibn 'Awf, from Abu Hurayrah, from the Messenger of Allah (peace and blessings of Allah be upon him) who said: "The injury caused by an animal is exempt from liability (jabar), the well is exempt from liability (jabar), and the mine is exempt from liability (jabar), and in the buried treasure (rikaz) is one-fifth."