Musannaf Ibn Abi Shayba 13:544

Abu Bakr narrated to us, he said: Ibn al-Mubarak narrated to us, from al-Zuhri, from Sa’id ibn al-Musayyib: That he used to dislike the sale of *al-muwasafa*. And *al-muwasafa* is that you describe a commodity to a man which you do not possess. And he disliked that you show a man a garment that is not yours, then you say, "Do you have a need for this?" so that you may buy it to sell it to him.