Musannaf Ibn Abi Shayba 13:855

Abu Bakr narrated to us, he said: Abu Mu'awiyah narrated to us, from al-A'mash, from Khaythama, from al-Aswad, who said: Abdullah said to me: Beware of selling *al-muhaffalat* (animals whose milk has been withheld to deceive the buyer), for it is a deception, and deception is not lawful.