Musnad Ahmad 27:656

Muhammad ibn Abdullah narrated to us, Ibn Abi Dhi’b narrated to us, from Uthman ibn Abdullah ibn Suraqah, who said: I asked Ibn Umar about the selling of fruits. He said: "The Messenger of Allah (peace and blessings of Allah be upon him) forbade the selling of fruits until the blight has passed." I said: "And when is that?" He said: "Until the Pleiades rises."