(1) باب تَحْرِيمِ طَلاَقِ الْحَائِضِ بِغَيْرِ رِضَاهَا وَأَنَّهُ لَوْ خَالَفَ وَقَعَ الطَّلاَقُ وَيُؤْمَرُ بِجْعَتِهَا
Anas b. Sirin reported that he had heard Ibn 'Umar (Allah be pleased with them) as saying. I divorced my wife while she was in the state of menses. 'Umar (Allah be pleased with him) came to Allah's Apostle (ﷺ) and informed him about it, whereupon he (Allah's Apostle) said:
Command him to take her back and when she is pure, then divorce her. I said to Ibn 'Umar Allah be pleased with them): Did you count that pronouncement of divorce? He said: Why not?
Reference: Sahih Muslim 1471 p
In-book reference: Book 18, Hadith 16
USC-MSA web (English) reference(deprecated numbering scheme): Book 9, Hadith 3487