Sahih al-Bukhari 2355
Sahih al-Bukhari · Book 42: Distribution of Water · If one digs a well and somebody falls in it and dies
Narrated Abu Huraira:
حَدَّثَنَا مَحْمُودٌ ، أَخْبَرَنَا عُبَيْدُ اللَّهِ ، عَنْ إِسْرَائِيلَ ، عَنْ أَبِي حَصِينٍ ، عَنْ أَبِي صَالِحٍ ، عَنْ أَبِي هُرَيْرَةَ ـ رضى الله عنه ـ قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " الْمَعْدِنُ جُبَارٌ، وَالْبِئْرُ جُبَارٌ، وَالْعَجْمَاءُ جُبَارٌ، وَفِي الرِّكَازِ الْخُمُسُ " .
Allah's Messenger (ﷺ) said, "No bloodmoney will be charged if somebody dies in a mine or in a well or is killed by an animal; and if somebody finds a treasure in his land he has to give one-fifth of it to the Government."