Musannaf Ibn Abi Shayba 13:1866

Abu Bakr narrated to us, he said: Ali bin Hashim narrated to us, from Ibn Abi Layla, from Atiyyah, from Abu Sa’id, from the Prophet (may Allah bless him and grant him peace), who said: "Do not purchase fruit until its ripeness becomes apparent." They said: "And what is its ripeness becoming apparent?" He said: "Until the majority of it is gone and its goodness becomes pure."