Musannaf Ibn Abi Shayba 10:728

Abu Bakr narrated to us, he said: Abda bin Sulayman narrated to us, from Sa’id bin Abi Arubah, from Qatadah, from Sa’id bin al-Musayyib, and from Abu Ma’shar, from Ibrahim; they both said: The waiting period of the woman who seeks khul’ (divorce initiated by the wife) is the waiting period of the divorced woman.