Ibn Sirin reported,

For twenty years, people whom I had no reason to doubt kept telling me that Ibn Umar had divorced his wife with three pronouncements while she was menstruating, and that he was ordered to take her back. I did not accuse them of lying, yet I could not properly verify the report, until I met Abu Ghallab Yunus bin Jubayr al-Bahili, a man of firm reliability. He told me that he had asked Ibn Umar about it, and Ibn Umar related to him that he had divorced his wife with a single pronouncement while she was menstruating, and was ordered to take her back.Yunus bin Jubayr asked, "Was that pronouncement counted against him as a divorce?"Ibn Umar replied, "Of course. What else, if a man falls short or behaves foolishly?"

Muslim 3661

Sahih

و حدثني علي بن حجر السعدي حدثنا إسمعيل بن إبراهيم عن أيوب

عن ابن سيرين قال

مكثت عشرين سنة يحدثني من لا أتهم أن ابن عمر طلق امرأته ثلاثا وهي حائض فأمر أن يراجعها فجعلت لا أتهمهم ولا أعرف الحديث حتى لقيت أبا غلاب يونس بن جبير الباهلي وكان ذا ثبت فحدثني أنه سأل ابن عمر فحدثه أنه طلق امرأته تطليقة وهي حائض فأمر أن يرجعها قال قلت أفحسبت عليه قال فمه أو إن عجز واستحمق

مسلم 3661صحيح
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 3661
Muslim 3661