Hadith 10:1271
Abu Bakr narrated to us, he said: Hafs bin Ghiyath narrated to us, from Ash'ath, from Ibn Sirin, who said: Abdullah said: "The waiting period of the divorced woman is by menstrual cycles, even if it takes a long time." Hafs said: "He mentioned the Sunnah and elaborated."
حدثنا أبو بكر قال نا حفص بن غياث عن أشعث عن بن سيرين قال قال عبد الله عدة المطلقة بالحيض وإن طالت قال حفص فذكر السنة وأكثر