Ibn Majah

the Messenger of Allah divorced Hafsah then took her back.

the Messenger of Allah said: What is wrong with people who play with the limits imposed by Allah, and one of them says: "I divorce you, I take you back, I divorce you?"

the Messenger of Allah said: "The most hated of permissible things to Allah is divorce. "

"I divorced my wife when she was menstruating. 'Umar mentioned that to the Messenger of Allah and he said: 'Tell him to take her back until she becomes pure (i.e., her period ends), then she has her period (again), then she becomes pure (again), then if he wishes he may divorce her before having sexual relations with her, and if he wishes he may keep her. This is the waiting period that Allah has enjoined.'"

"Divorce according to the Sunnah means divorcing her when she is pure, ( i.e., not menstruating) and without having had intercourse with her (during that cycle)."

"Divorce according to the Sunnah means divorcing her with one divorce in each cycle when she is pure, then when she becomes pure the third time, then he pronounces divorce again, and after that she must wait one more menstrual cycle."

"I asked Ibn 'Umar about a man who divorced his wife when she was menstruating. He said: 'Do you know 'Abdullah bin 'Umar? He divorced his wife when she was menstruating then 'Umar came to the Prophet (ﷺ) (and told him what had happened). He ordered him to take her back.' I said: 'Will that be counted (as a divorce)?' He said: 'Do You think he was helpless and behaving foolishly? [i.e., Yes, it counts (as a divorce).]."'

he divorced his wife when she was menstruating, and 'Umar mentioned that to the Prophet (ﷺ). He said: "Tell him to take her back then divorce her when she is pure (not menstruating) or pregnant."

"I said to Fatimah bint Qais: 'Tell me about your divorce.' She said: 'My husband divorced me three times when he was leaving for Yemen, and the Messenger of Allah (ﷺ) allowed that."'

was asked about a man who divorced his wife then had intercourse with her, and there were no witnesses to his divorcing her or his taking her back. 'Imran said: "You have divorced (her) in a manner that is not according to the Sunnah, and you have taken her back in a manner that is not according to the Sunnah. Bring people to witness your divorcing her and taking her back."