Al-Kāfi - Volume 5 > Advance Payment for Buying Slaves and Animals
Hadith #4

4- مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدٍ عَنِ ابْنِ فَضَّالٍ عَنِ ابْنِ بُكَيْرٍ عَنْ عُبَيْدِ بْنِ زُرَارَةَ عَنْ أَبِي عَبْدِ اللهِ (عَلَيْهِ السَّلام) قَالَ لا بَأْسَ بِالسَّلَمِ فِي الْحَيَوَانِ إِذَا سَمَّيْتَ شَيْئاً مَعْلُوماً.

4. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from ibn Faddal from ibn Bukayr from ‘Ubayd ibn Zurarah who has said the following: “Abu ‘Abd Allah, ‘Alayhi al-Salam, has said, ‘Advance payment to buy an animals is not unlawful if it (the animal) is clearly made known.’”