Sahih al-Bukhari 5253
Sahih al-Bukhari · Book 68: Divorce · Divorce during the menses is counted as one legal divorce.
Narrated Ibn `Umar:
وَقَالَ أَبُو مَعْمَرٍ حَدَّثَنَا عَبْدُ الْوَارِثِ ، حَدَّثَنَا أَيُّوبُ ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ ، عَنِ ابْنِ عُمَرَ ، قَالَ حُسِبَتْ عَلَىَّ بِتَطْلِيقَةٍ .
(Divorcing my wife during her menses) was counted as one legal divorce.