Chapter on Khums
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 1|Chapter 7
وَ سَأَلَ عُبَيْدُ اَللَّهِ بْنُ عَلِيٍّ اَلْحَلَبِيُّ أَبَا عَبْدِ اَللَّهِ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلْكَنْزِ كَمْ فِيهِ فَقَالَ «اَلْخُمُسُ» وَ عَنِ اَلْمَعَادِنِ كَمْ فِيهَا فَقَالَ «اَلْخُمُسُ» وَ عَنِ اَلرَّصَاصِ وَ اَلصُّفْرِ وَ اَلْحَدِيدِ وَ مَا كَانَ مِنَ اَلْمَعَادِنِ كَمْ فِيهَا فَقَالَ «يُؤْخَذُ مِنْهَا كَمَا يُؤْخَذُ مِنْ مَعَادِنِ اَلذَّهَبِ وَ اَلْفِضَّةِ ».
Ubaydullah ibn Ali al-Halabi asked Abu Abdullah Imam Jafar ibn Muhammad Al-Sadiq عليه السلام about buried treasure: "How much is due on it?" Imam عليه السلام replied: "The Khums (one-fifth)." He then asked about mines: "How much is due on them?" Imam عليه السلام replied: "The Khums." He further asked about lead, brass, iron, and other mineral types: "How much is due on them?" The Imam عليه السلام replied: "The same is taken from them as is taken from mines of gold and silver."
- Ṣaḥīḥ al-Faqīh