‘A’isha told of hearing God’s Messenger say, “There is no divorce or emancipation in case of ighlaq." It is said that the meaning of ighlaq is “constraint”.
Narrated Abu Huraira reported God’s Messenger as saying, “There are three things which, whether undertaken seriously or in jest, are treated as serious:
marriage, divorce and taking back a wife after a divorce which is not final.”
Tirmidhi and Abu Dawud transmitted it, Tirmidhi saying this is a hasan gharib tradition.
Rukana b. 'Abd Yazid said he divorced his wife Suhaima absolutely and when the Prophet was informed of that he said, “I swear by God that I meant it to be only a single utterance of divorce.” God’s Messenger asked him if that was so, and when he assured him that it was, he restored her to him. Then he divorced her the second time in the time of ‘Umar and the third time in the time of ‘Uthman.
Abu Dawud, Tirmidhi, Ibn Majah and Darimi transmitted it, but only Abu Dawud mentioned the second and third time (See Abu Dawud’s Sunan, Talaq, 14).