Divorce

Bukhari :: Book 7 :: Volume 63 :: Hadith 187

Narrated 'Aisha:

A man divorced his wife thrice (by expressing his decision to divorce her thrice), then she married another man who also divorced her. The Prophet was asked if she could legally marry the first husband (or not). The Prophet replied, "No, she cannot marry the first husband unless the second husband consummates his marriage with her, just as the first husband had done."