سورة Al-Baqarah ( The Cow ) - الآية 230

And if he hath divorced her (the third time), then she is not lawful unto him thereafter until she hath wedded another husband. Then if he (the other husband) divorce her it is no sin for both of them that they come together again if they consider that they are able to observe the limits of Allah. These are the limits of Allah. He manifesteth them for people who have knowledge.