Sahih Muslim Book 10, Hadith Number 3635.

Chapter : Command pertaining to the selling of animal whose udder is tied up.

Abu Huraira (Allah be pleased with him) reported Allah’s Messenger (may peace be upon him) as saying: He who buys a goat with its udder tied up has the option to retain the goat if he so desires or return it within three days, and in case he returns it he should do so along with a sa’ of dates.