The Messenger of Allah ﷺ said, "A well is exempt from liability, an animal is exempt from liability, and a mine is exempt from liability. As for buried treasure, a fifth is due on it."
أخبرنا يعقوب بن إبراهيم حدثنا هشيم أنبأنا منصور وهشام عن ابن سيرين
قال رسول الله ﷺ البئر جبار والعجماء جبار والمعدن جبار وفي الركاز الخمس