Musnad Ahmad 27:94

Sufyan narrated to us, from al-Zuhri, from Salim, from his father: "The Messenger of Allah, peace and blessings of Allah be upon him, forbade the selling of fruit for dates." Sufyan said: "This is how we memorized it: fruit for dates." And Zayd ibn Thabit informed them: "That the Messenger of Allah, peace and blessings of Allah be upon him, granted a concession regarding *al-’araya* (the sale of fresh dates on the tree for dried dates of equal measure)."