Musannaf Ibn Abi Shayba 13:3128

Abu Bakr narrated to us, he said: Abu Usama narrated to us, from Hisham, from al-Hasan and Muhammad, that they used to see no harm in a man purchasing a sale, some of it for cash and some of it on credit, then selling it for a profit. They said: "His companion knows from it the same as he knows."