Musnad Ahmad 33:323

Yahya narrated to us, Salim ibn Hayyan narrated to us, Sa'id ibn Mina narrated to us, I heard Jabir ibn Abdullah saying: "The Messenger of Allah (peace and blessings of Allah be upon him) forbade the selling of fruit until it *tashqah* (shows signs of ripening)." I said: "When does it *tashqah*?" He said: "It turns red or yellow, and it can be eaten from."