Musannaf Ibn Abi Shayba 10:1007

Abu Bakr narrated to us, he said: Abdullah ibn Idris narrated to us, from Hisham, from Qays ibn Sa'd, from Bukayr ibn Abdullah ibn al-Ashajj, from Sulayman ibn Yasar, from Zayd ibn Thabit, who said: "If a woman experiencing postpartum bleeding is divorced, do not count that blood [as part of the waiting period]."