Musnad Ahmad 30:2905

'Abd al-Rahman narrated to us, Hammad narrated to us, from Muhammad—meaning Ibn Ziyad—who said: I heard Abu Hurayrah saying: I heard Abu al-Qasim (may Allah bless him and grant him peace) saying: "The dumb beast is a *jubar* (liability for which there is no compensation), the mine is a *jubar*, and the well is a *jubar*. And in the *rikaz* (buried treasure), there is one-fifth."