Anas bin Sirin reported,

I asked Ibn Umar about his wife whom he had divorced.He said, "I divorced her while she was menstruating, and that was mentioned to Umar, who in turn mentioned it to the Prophet ﷺ. The Prophet ﷺ said, 'Tell him to take her back, and when she becomes pure, let him divorce her during her state of purity.' So I took her back, then divorced her during her state of purity."I asked, "Did you count that pronouncement of divorce, the one you made while she was menstruating?"He replied, "Why would I not count it? Even if I had been incapable and acted foolishly."

Muslim 3666

Sahih

حدثنا يحيى بن يحيى أخبرنا خالد بن عبد الله عن عبد الملك

عن أنس بن سيرين قال

سألت ابن عمر عن امرأته التي طلق فقال طلقتها وهي حائض فذكر ذلك لعمر فذكره للنبي ﷺ فقال مره فليراجعها فإذا طهرت فليطلقها لطهرها قال فراجعتها ثم طلقتها لطهرها قلت فاعتددت بتلك التطليقة التي طلقت وهي حائض قال ما لي لا أعتد بها وإن كنت عجزت واستحمقت

مسلم 3666صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Divorce
Chapter
Prohibition of divorcing a menstruating woman without her consent, and that if one does so the divorce still takes effect and he is commanded to take her back
Numbering
Darussalam 3666
Muslim 3666