Muwatta Imam Malik (Riwayat Ibn al-Qasim)

And with the same chain of narration, it is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "A grazing animal (if it causes damage) is without liability (there is no compensation for it); the same ruling applies to wells and minerals, and one-fifth is due (for Allah) from buried treasure."

And with this chain (it is narrated from Sayyiduna Abu Hurairah, may Allah be pleased with him) that the Messenger of Allah, peace and blessings be upon him, said: "The injury caused by livestock is without liability (i.e., there is no blood money or penalty upon its owner), and (any injury or death) in a mine is without liability (i.e., there is no blood money or penalty upon its owner), and a well is without liability (i.e., if someone falls into a well, there is no blood money or penalty upon its owner), and in the case of a buried treasure (when found), one-fifth (must be set aside for Allah)."