(76) باب الرَّجْعَةِ
It was narrated from Ibn 'Umar that he divorced his wife when she was menstruating, and the Messenger of Allah told him to take her back.
Reference: Sunan an-Nasa'i 3558
In-book reference: Book 27, Hadith 172
English translation: Vol. 4, Book 27, Hadith 3588