Musnad Abu Ya'la al-Mawsili 118:57

Abu Musa narrated to us, al-Hasan ibn Musa narrated to us, Ibn Lahi'ah narrated to us, Yazid ibn Abi Habib and 'Uqayl narrated to us, from Ibn Shihab, from Anas ibn Malik, that the Messenger of Allah (may Allah bless him and grant him peace) forbade a man from selling the stud-fee of his horse.