{ If a man divorces a woman, then she is no longer lawful to him after that until she has marital relations with a husband other than him } Al-baqara 230

The word of the Most High { If a man divorces a woman, then she is not lawful to him after that until she has marital relations with a husband other than him } : that is, if a man divorces his woman by a third pronouncement after having conveyed divorce to her by two pronouncements, then she is not lawful to him until she has marital relations with a husband other than him, that is, until a different husband has intercourse with her in a legitimate marriage. If someone has intercourse with her outside of legitimate marital relations, even if she is what the right hand possesses [milk al-yamin, i.e. a slave], she is not lawful to the first husband, since it did not occur in marriage. If she marries, but the husband does not enter her, she is not lawful for the former husband.