Musannaf Ibn Abi Shayba 13:1627

Abu Bakr narrated to us, he said: Waki’ narrated to us, from Sufyan, from Jabir, from al-Qasim, from Masruq: That he disliked the sale of "ten for twelve." He said: He says, "I bought it for such and such, and I sell it to you for such and such."