Bukhari :: Book 7 :: Volume 63 :: Hadith 179

Narrated Anas bin Sirin:

Ibn 'Umar said: "I divorced my wife while she was menstruating. 'Umar mentioned that to the Prophet . The Prophet said, (to my father), "Let your son take her back." I asked (Ibn 'Umar), "Is such a divorce counted (i.e. as one legal divorce)?" Ibn 'Umar said, "Of course." Narrated Yunus bin Jubair: Ibn 'Umar said, "The Prophet said to 'Umar, 'Order him (Ibn 'Umar) to take her back.' " I asked, "Is such a divorce counted (as one legal divorce)?" Ibn 'Umar said, "What do you think if someone becomes helpless and foolish?"

Source materials are from the University of Southern California MSA site
Hadith eBooks converted from Imaan Star