Musannaf Ibn Abi Shayba 10:831

Abu Bakr narrated to us, he said: Ibn Idris narrated to us, from Malik ibn Anas, from al-Zuhri, from Sa’id ibn al-Musayyib and Abu Bakr ibn Abd al-Rahman ibn al-Harith ibn Hisham, they both said: When four months have passed in *ila* (oath of abstention), it is a divorce, and he is more entitled to take her back.