The Divorce According To The Sunnah
Abd Allah bin Umar said that he divorced his wife while she was menstruating during the time of the Apostle of Allaah(ﷺ). So ‘Umar bin Al Khattab asked the Apostle of Allaah (ﷺ) about this matter. The Apostle of Allaah(ﷺ) said “Order him, he must take her back and keep her back till she is purified, then has another menstrual period and is purified. Thereafter if he desires he may divorce her before having intercourse with her, for that is the period of waiting which Allaah the Glorified has commanded for the divorce of women.”
A Man Takes His Wife Back Without Any Witnesses

Imran ibn Husayn was asked about a person who divorces his wife, and then has intercourse with her, but he does not call any witness to her divorce nor to her restoration. He said: You divorced against the sunnah and took her back against the sunnah. Call someone to bear witness to her divorce, and to her return in marriage, and do not repeat it.
Regarding A Divorce Before The Marriage
The Prophet (ﷺ) said: There is no divorce except in what you possess; there is no possession, there is no sale transaction till you possess. The narrator Ibn as-Sabbah added: There is no fulfilling a vow till you possess
The above tradition has also been transmitted by ‘Amr bin Shu’aib through a different chain of narrators to the same effect. This version adds “If anyone swears an oath to do an act of disobedience to GOD, his oath is not valid, and if anyone swears an oath to sever relationship, his oath is not valid(i.e., he must not fulfill it)
Chapter: Regarding Divorcing By Mistake
Muhammad ibn Ubayd ibn Abu Salih who lived in Ayliya said:
I went out with Adi ibn Adi al-Kindi till we came to Mecca. He sent me to Safiyyah daughter of Shaybah who remembered a tradition (that she had heard) from Aisha. She said: I heard Aisha say: I heard the Messenger of Allah (ﷺ) say: There is no divorce or emancipation in case of constraint or duress (ghalaq).
 
Abu Dawud said: I think ghalaq means anger.
Regarding A Divorce That Was Said In Jest
The Prophet (ﷺ) said: 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)
The Abrogation Of Taking Back A Wife After The Third Divorce
Divorced women shall wait concerning themselves for three monthly periods. Nor is it lawful for them to hide what Allah hath created in their wombs. This means that if a man divorced his wife he had the right to take her back in marriage though he had divorced her by three pronouncements. This was then repealed (by a Qur'anic verse). Divorce is only permissible twice.
Umar bin Al Khattab reported the Apostle of Allaah(ﷺ) as saying “Actions are to be judged only by intentions and a man will have only what he intended. When one’s emigration is to Allaah and His Apostle, his emigration is to Allaah and His Apostle but his emigration is to a worldly end at which he aims or to a woman whom he marries , his emigration is to that for which he emigrated.
Abd Allah bin Ka’b reported “I heard Ka’ab bin Malik. He then narrated his story about the battle of Tabuk.(Narrating the story) he added “When forty out of fifty days passed”, the messenger of the Apostle of Allaah(ﷺ) came and said “The Apostle of Allaah(ﷺ) has commanded you to keep away from your wife. He said “So, I (Ka’b bin Malik)” said “Should I divorce her or what should I do? He said “No, but only keep away from her and do not go near her”. So, I said to my wife “Go to your people and live with them until Allaah, the exalted makes a decision in this matter.”
Regarding Whisperings Of Divorce
 
Abu Hurairah reported the Prophet (ﷺ) as saying “Allah has ignored for my community what comes to their mind, so long as they do not act or pronounce words to that effect.”