Abdullah bin Umar reported,

I divorced my wife while she was menstruating, so Umar mentioned this to the Messenger of Allah ﷺ.The Messenger of Allah ﷺ became angry and said, "He must take her back and keep her until she completes another menstrual cycle apart from the one in which he divorced her. Then, if he still wishes to divorce her, let him do so when she is pure and before he has touched her. That is the divorce during the waiting period as Allah the Exalted has commanded."Abdullah had pronounced one divorce, and it was counted against him as a divorce, then Abdullah took her back as he had been commanded.

Ahmad 6141

Sahih

حدثنا يعقوب أخبرني ابن أخي ابن شهاب عن عمه أخبرنا سالم بن عبد الله أن

عبد الله بن عمر قال

طلقت امرأتي وهي حائض فذكر عمر ذلك لرسول الله ﷺ قال فتغيظ رسول الله ﷺ ثم قال ليراجعها حتى تحيض حيضة مستقبلة سوى حيضتها التي طلقها فيها فإن بدا له أن يطلقها فليطلقها طاهرا من حيضتها قبل أن يمسها فذلك الطلاق للعدة كما أمر الله تعالى وكان عبد الله طلقها تطليقة فحسبت من طلاقها وراجعها عبد الله كما أمره

أحمد 6141صحيح
Contents
Reference
Commentary
Ayat
Collection
Musnad Ahmad
Book
Abdullah bin Umar
Numbering
Darussalam 6141
Ahmad 6141