Musnad Abu Ya'la al-Mawsili 109:26

Ishaq narrated to us, Abbad bin al-Awwam narrated to us, Hajjaj informed us, from Abu al-Zubayr, from Jabir, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no harm in [exchanging] animals, two for one, hand-to-hand (spot transaction). But there is no good in it if it is on credit (nasi'ah)."