Musannaf Ibn Abi Shayba 13:2162

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Shu’bah narrated to us, from al-Hakam, from ‘Abd al-Rahman ibn Abi Layla, from a man among the companions of the Prophet, who said: The Prophet, may Allah bless him and grant him peace, said: "Whoever buys a *musarrah* (an animal whose milk has been withheld in the udder to deceive the buyer) ewe, he has the choice of two options regarding it: if he returns it, he returns with it a *sa’* of dates or a *sa’* of food."