(2) باب إِذَا طُلِّقَتِ الْحَائِضُ يُعْتَدُّ بِذَلِكَ الطَّلاَقِ
Narrated Ibn `Umar:
(Divorcing my wife during her menses) was counted as one legal divorce.
Reference: Sahih al-Bukhari 5253
In-book reference: Book 68, Hadith 3
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 7, Book 63, Hadith 180