Musannaf Ibn Abi Shayba 13:1861

Abu Bakr narrated to us, he said: Abu al-Ahwas narrated to us, from Zayd ibn Jubayr, he said: A man asked Ibn Umar about the buying of fruit. He said: The Messenger of Allah (may Allah bless him and grant him peace) forbade that fruit be sold until its ripeness becomes apparent.