Narrated `Abdullah bin Mas`ud: Whoever buys a sheep which has not been milked for a long time, has the option of returning it along with one Sa of dates; and the Prophet forbade going to meet the seller on the way (as he has no knowledge of the market price and he may sell his goods at a low price).
Hadith Referenceصحيح البخاري / كتاب البيوع / 2149
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة
Hadith Commentary: Imam Bukhari rahimahullah has narrated the aforementioned report from Abdullah ibn Mas’ud radi Allahu anhu so that those who disparage Abu Hurairah radi Allahu anhu as being non-juristic and thereby reject the aforementioned hadith may reflect upon themselves, for the content of this hadith is also narrated from Abdullah ibn Mas’ud radi Allahu anhu, whom these very people accept as an Imam in jurisprudence (fiqh) and independent reasoning (ijtihad).
On this subject, Imam Ibn al-Qayyim has written extensively in "I’lam al-Muwaqqi’in".
A narration from Abdullah ibn Mas’ud radi Allahu anhu is reported in these words: “I swear by Allah that the truthful and trusted Messenger of Allah sallallahu alayhi wa sallam declared the sale of animals with withheld milk to be a deception, and said that it is not permissible to deceive a Muslim in this manner.” (Sunan Ibn Majah, Kitab al-Tijarat, Hadith: 2241)
Source: Hidayat al-Qari: Commentary on Sahih Bukhari, Urdu, Page: 2149
Narrated Ibn Mas'ud (RA): If anyone buys a goat whose udder has been tied up and he returned it, he must return it with one Sa'. [Reported by al-Bukhari]. al-Isma'ili added: "of dates."