Chapter on Khums
Man Lā Yaḥḍuruh al-Faqīh|Volume 2|Book 1|Chapter 7
وَ سَأَلَ مُحَمَّدُ بْنُ مُسْلِمٍ أَبَا جَعْفَرٍ عَلَيْهِ اَلسَّلاَمُ: عَنِ اَلْمَلاَّحَةِ فَقَالَ «وَ مَا اَلْمَلاَّحَةُ» فَقُلْتُ أَرْضٌ سَبِخَةٌ مَالِحَةٌ يَجْتَمِعُ فِيهَا اَلْمَاءُ فَيَصِيرُ مِلْحاً فَقَالَ «مِثْلُ اَلْمَعْدِنِ فِيهِ اَلْخُمُسُ» قُلْتُ فَالْكِبْرِيتُ وَ اَلنِّفْطُ يُخْرَجُ مِنَ اَلْأَرْضِ فَقَالَ «هَذَا وَ أَشْبَاهُهُ فِيهِ اَلْخُمُسُ ».
Muhammad ibn Muslim asked Abu Ja’far Imam Muhammad ibn Ali Al-Baqir عليه السلام about salt flats. The Imam asked: "What are salt flats?" I replied: "They are salty, barren lands where water collects and turns into salt." The Imam عليه السلام said: "It is like a mine; Khums is due on it." I asked: "What about sulfur and oil extracted from the earth?" Imam عليه السلام replied: "These and similar things also require Khums."
- Ṣaḥīḥ al-Faqīh, p. 85