Musannaf Ibn Abi Shayba 10:1010

Abu Bakr narrated to us, he said: Waki’ narrated to us, he said: Jarir ibn Hazim narrated to us, from Qays ibn Sa’d, from Bukayr ibn ‘Abd Allah ibn al-Ashajj, from Sulayman ibn Yasar, from Zayd ibn Thabit, who said: If a man divorces his wife while she is experiencing postpartum bleeding, her postpartum blood is not counted as part of her waiting period (‘iddah).