Musannaf Ibn Abi Shayba 13:502

Abu Bakr narrated to us, he said: Ibn Abi Za’idah narrated to us, from Muhammad ibn ‘Amr, from Abu Salamah, from Abu Hurayrah, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever sells two sales in one sale, then for him is the lesser of the two, or [it is] usury."