Majma al-Zawaid — Hadith 6527

Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that the Prophet (peace and blessings be upon him) said: "Do not hold back the milk in the udders of camels and goats (tasriyah) in order to sell them! Whoever buys a goat whose milk has been held back has one of two options (that is, if he wishes, he may cancel the sale): if he returns it, he is to return it with a sa' of dates." (Allamah al-Haythami says:) I say: Abu Dawud and Ibn Majah also recorded it, but both of them have the wording: "He is to return wheat equal to its milk or twice that," mentioning wheat here in place of dates.
Al-Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains a narrator, Layth bin Abi Sulaym, who is thiqah (trustworthy) but a mudallis (one who conceals defects in the chain), and the rest of its narrators are the narrators of the Sahih.