Bukhari :: Book 7 :: Volume 63 :: Hadith 235

Narrated Ibn 'Umar: The Prophet made a man and his wife carry out Lian, and the husband repudiated her child. So the Prophet got them separated (by divorce) and decided that the child belonged to the mother only.

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