(4) باب الطَّلاَقِ لِغَيْرِ الْعِدَّةِ
It was narrated from Ibn 'Umar that he divorced his wife when she was menstruating, but the Messenger of Allah told him to take her back, and divorce her when she was pure (not menstruating).
Reference: Sunan an-Nasa'i 3398
In-book reference: Book 27, Hadith 10
English translation: Vol. 4, Book 27, Hadith 3427