Abdullah bin Abbas (may Allah be pleased with them both) said: "There are four ways of divorce; two of them are permissible, and two of them are forbidden. As for the two permissible ways, they are that a man divorces his wife while she is in a state of purity, without having had intercourse with her, or he divorces his wife when she is pregnant and her pregnancy is evident. As for the two ways that are forbidden, they are that a man divorces his wife during her menstruation, or he divorces her after having intercourse with her, in which it is not known whether as a result of that intercourse she has become pregnant or not."