I heard Abu Qasim ﷺ say, "Injury caused by an animal carries no liability, a well carries no liability, and a mine carries no liability. On buried treasure, a fifth is due."
حدثنا عفان قال حدثنا حماد عن محمد بن زياد قال سمعت
سمعت أبا القاسم ﷺ يقول الدابة العجماء جبار والبئر جبار والمعدن جبار وفي الركاز الخمس
Its isnad is sahih, and it has appeared many times before. See it also in Muslim 3/1334, no. 1710, Abu Dawud 4/196, no. 4593, Tirmidhi 3/25, no. 642, Nasai 5/44-45, no. 2495, and Ibn Majah 2/891, no. 2673.