Musnad Abu Ya'la al-Mawsili 153:114

Suwayd ibn Sa'id narrated to us, Yahya—meaning ibn Zakariyya—narrated to me, he said: Muhammad ibn 'Amr narrated to me, from Salim ibn 'Abd Allah, from his father, who said: The Messenger of Allah (may Allah bless him and grant him peace) said: "The sale of fruit is not valid until its ripeness becomes apparent."