Musnad Ahmad 27:563

Yazid ibn Harun narrated to us, he said: Ibn Abi Dhi'b informed us, from Uthman ibn Abdullah ibn Suraqah, who said: We were on a journey and Ibn Umar was with us, so I asked him, and he said: "I saw the Messenger of Allah, peace and blessings of Allah be upon him, not performing voluntary prayers (tasbih) during travel, neither before the prayer nor after it." He said: And I asked Ibn Umar about the selling of fruits, and he said: "The Messenger of Allah, peace and blessings of Allah be upon him, forbade the selling of fruits until the blight (al-'ah) has passed." I said: "O Abu Abd al-Rahman, and what is the passing of the blight? What is the blight?" He said: "The rising of the Pleiades."