It is narrated from Sayyiduna Abu Hurayrah (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The wound (caused) by an animal, (injury) while extracting minerals, and (injury) from fire are unavenged (no compensation is due), and in buried treasure (rikaz) there is one-fifth (khumus)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الأشربة والحد فيها / 17694