Narrated Abu Hurairah:
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'
[Abu 'Eisa said:] 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.