Al-Kāfi - Volume 5 > Milk, Wool and Ghee of Sheep Given for their Maintenance
Hadith #4

4- عَلِيُّ بْنُ إِبْرَاهِيمَ عَنْ أَبِيهِ عَنِ ابْنِ مَحْبُوبٍ عَنْ عَبْدِ اللهِ بْنِ سِنَانٍ قَالَ سَأَلْتُ أَبَا عَبْدِ اللهِ (عَلَيْهِ السَّلام) عَنْ رَجُلٍ دَفَعَ إِلَى رَجُلٍ غَنَمَهُ بِسَمْنٍ وَدَرَاهِمَ مَعْلُومَةٍ لِكُلِّ شَاةٍ كَذَا وَكَذَا فِي كُلِّ شَهْرٍ قَالَ لا بَأْسَ بِالدَّرَاهِمِ فَأَمَّا السَّمْنُ فَمَا أُحِبُّ ذَاكَ إِلا أَنْ يَكُونَ حَوَالِبَ فَلا بَأْسَ.

4. Ali ibn Ibrahim has narrated from his father from ibn Mahbub from ‘Abd Allah ibn Sinan who has said the following: “This is concerning my question before abu ‘Abd Allah, ‘Alayhi al-Salam, about the case of a man who gave his sheep to a man for maintenance in exchange for Ghee and a certain amount of dirham for every sheep every month. He (the Imam) said, ‘It is not unlawful in exchange for dirham, however, for ghee, I do not like unless they give milk.’”