Divorce -
The sister of Ma'qil bin Yasar was married to a man and then that man divorced her and remained away from her till her period of the 'Iddah expired. Then he demanded for her hand in marriage, but Ma'qil got angry out of pride and haughtiness and said, "He kept away from her when he could still retain her, and now he demands her hand again?" So Ma'qil disagreed to remarry her to him. Then Allah revealed: 'When you have divorced women and they have fulfilled the term of their prescribed period, do not prevent them from marrying their (former) husbands.' (2.232) So the Prophet (ﷺ) sent for Ma'qil and recited to him (Allah's order) and consequently Ma'qil gave up his pride and haughtiness and yielded to Allah's order.
AI Summary
Ibn `Umar divorced his wife while she was menstruating. The Prophet (ﷺ) ordered Ibn `Umar to take her back and keep her until she becomes clean, then wait for her next period and menstruation, and then he may either retain her or divorce her before having sexual intercourse. This is the prescribed period which Allah has fixed for the women meant to be divorced.