(1) باب تَحْرِيمِ طَلاَقِ الْحَائِضِ بِغَيْرِ رِضَاهَا وَأَنَّهُ لَوْ خَالَفَ وَقَعَ الطَّلاَقُ وَيُؤْمَرُ بِجْعَتِهَا
Ibn 'Umar (Allah be pleased with them) reported that he divorced his wife during the period of menses. 'Umar (Allah be, pleas'ed with him) asked Allah's Apostle (ﷺ), and he commanded him ('Abdullah b. 'Umar) to have her back and then allow her respite until she enters the period of the second menses, and then allow her respite until she is purified, then divorce her (finally) before touching her (having a sexual intercourse with her), for that is the prescribed period which Allah commanded (to be kept in view) for divorcing the women. When Ibn 'Umar (Allah be pleased with them) was asked about the person who divorces his wife in the state of menses, he said:
If you pronounced one divorce or two, Allah's Messenger (ﷺ) had commanded him to take her back, and then allow her respite until she enters the period of the second menses, and then allow her respite until she is purified, and then divorce her (finally) before touching her (having a sexual intercourse with her) ; and if you have pronounced (three divorces at one and the same time) you have in fact disobeyed your Lord with regard to what He commanded you about divorcing your wife. But she is however (finally separated from you).
Reference: Sahih Muslim 1471 e
In-book reference: Book 18, Hadith 5
USC-MSA web (English) reference(deprecated numbering scheme): Book 9, Hadith 3477