Yahya bin Abi Anisa يحيى بن أبي أنيسة · The Book on Business

That the Prophet (ﷺ) said: "Whoever purchases an animal that has not been milked, then he retains the option for three days. If he returns it, then he is to return with it a Sa' of food, not Samra' " The meaning of "Not Samra'" is "not wheat." This Hadith is Hasan Sahih. This Hadith is acted upon according to our companions, among them Ash-Shafi'i, Ahmad, and Ishaq.