Musannaf Ibn Abi Shayba 13:1135

Abu Bakr narrated to us, he said: Hafs narrated to us, from Layth, from Tawus, that he used to dislike the selling of ghee and the selling of oil while adding [the weight of] the containers, such and such [amount]. And he would say: "No, except by pouring [measurement] or by weight."