Hadith 10:7
Abu Bakr narrated to us, he said: Abu al-Ahwas narrated to us, from Mansur, from Abu Wa'il, who said: Ibn Umar divorced his wife while she was menstruating. So Umar came to the Prophet, may Allah bless him and grant him peace, and informed him. The Prophet, may Allah bless him and grant him peace, said: "Command him to take her back, then let him divorce her while she is pure, without having had intercourse [with her]."
حدثنا أبو بكر قال نا أبو الأحوص عن منصور عن أبي وائل قال طلق بن عمر امرأته وهي حائض فأتى عمر النبي صلى الله عليه وسلم فأخبره فقال النبي صلى الله عليه وسلم مره فليراجعها ثم ليطلقها طاهرا في غير جماع