Musannaf Ibn Abi Shayba 13:2784

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Malik ibn Anas narrated to us, from al-Zuhri, from Sa’id ibn al-Musayyib and Abu Salamah, they both said: The Messenger of Allah (may Allah bless him and grant him peace) decreed the right of pre-emption (shuf’ah) as long as it has not been divided. But when the boundaries have been set, there is no pre-emption.