Musannaf Ibn Abi Shayba 13:1856

Abu Bakr narrated to us, he said: Sahl ibn Yusuf narrated to us, from Humayd, from Anas, who said: The Prophet (peace and blessings of Allah be upon him) forbade the selling of fruit until its ripeness becomes apparent. It was said to Anas: "And what is its ripeness becoming apparent?" He said: "It turns red or it turns yellow."