Sunan an-Nasa'i 3396
سنن النسائي#3396SahihIt was narrated from 'Abdullah that he issued a divorce to his wife when she was menstruating. So 'Umar went to inform the Prophet about that. The Prophet said to him:"Tell 'Abdullah to take her back, then, when she has performed Ghusl, let him leave her alone, until she menstruates (again). Then, when she performs Ghusl following that second period, he should not touch her until he divorces her. And if he wants to keep her, then let him keep her. That is the time when Allah has stated that women may be divorced
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiIsnaad Sahih
In-book reference: 27:8