Abu Hurayrah (may Allah be pleased with him) reported that the Prophet (may Allah's peace and blessings be upon him) said: "There is no compensation for one killed or wounded by an animal or by falling in a well or because of working in a mine, and one fifth is due on the buried treasure."
Abu Hurayrah (may Allah be pleased with him) reports what the Prophet (may Allah's peace and blessings be upon him) said about the liability for damage caused by an animal or by going down a well or a mine. He clarified that the damage caused by an animal entails no compensation. The same applies to the damage caused by going down a well or a mine and dying therein. This is because the animal, well, and mine cannot be held liable for compensation, nor can their owner be held liable as long as he did not commit any transgression or negligence. Then he mentioned that whoever finds a buried treasure from pre-Islamic times, be it big or small, then he must give out one-fifth of it because he acquired it without any difficulty or burden, and he keeps the rest for himself.