Al-Kāfi - Volume 5 > Milk, Wool and Ghee of Sheep Given for their Maintenance
Hadith #3

3- حُمَيْدُ بْنُ زِيَادٍ عَنِ الْحَسَنِ بْنِ مُحَمَّدِ بْنِ سَمَاعَةَ عَنْ بَعْضِ أَصْحَابِهِ عَنْ أَبَانٍ عَنْ مُدْرِكِ بْنِ الْهَزْهَازِ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) فِي الرَّجُلِ يَكُونُ لَهُ الْغَنَمُ فَيُعْطِيهَا بِضَرِيبَةٍ شَيْئاً مَعْلُوماً مِنَ الصُّوفِ أَوِ السَّمْنِ أَوِ الدَّرَاهِمِ قَالَ لا بَأْسَ بِالدَّرَاهِمِ وَكُرِهَ السَّمْنُ.

3. Humayd ibn Ziyad has narrated from al-Hassan ibn Muhammad ibn Sama‘ah from certain persons of his people from Aban from Mudrik ibn al-Hazhaz who has said the following: “This is concerning my question before abu ‘Abd Allah, ‘Alayhi al-Salam, about the case of a man who had sheep and gave them for their maintenance in exchange for their wool or Ghee or dirham. He (the Imam) said, ‘It is not unlawful.’ He disliked ghee.”