Abdullah bin Umar reported,

He informed him that he had divorced his wife while she was menstruating. Umar mentioned this to the Messenger of Allah ﷺ, and the Messenger of Allah ﷺ became angry about it. Then he said, "Let him take her back and keep her until she becomes pure, then menstruates, then becomes pure again. If he then decides to divorce her, let him divorce her while she is pure, before he has touched her. That is the waiting period as Allah عز وجل has commanded."

Bukhari 4908

Sahih

حدثنا يحيى بن بكير حدثنا الليث قال حدثني عقيل عن ابن شهاب قال أخبرني سالم أن

عبد الله بن عمر رضي الله عنهما

أخبره أنه طلق امرأته وهي حائض فذكر عمر لرسول الله ﷺ فتغيظ فيه رسول الله ﷺ ثم قال ليراجعها ثم يمسكها حتى تطهر ثم تحيض فتطهر فإن بدا له أن يطلقها فليطلقها طاهرا قبل أن يمسها فتلك العدة كما أمر الله عز وجل

البخاري 4908صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Tafsir
Chapter
His saying, "They say if we return to Madinah, the more honored will surely expel the more humble therefrom. But to Allah belongs all honor, and to His Messenger, and to the believers, but the hypocrites do not know"
Numbering
Darussalam 4908
Bukhari 4908