Sahih al-Bukhari 311
Sahih al-Bukhari · Book 6: Menstrual Periods · The I'tikaf of a woman who is bleeding in between her periods
Narrated `Aisha:
حَدَّثَنَا مُسَدَّدٌ ، قَالَ حَدَّثَنَا مُعْتَمِرٌ ، عَنْ خَالِدٍ ، عَنْ عِكْرِمَةَ ، عَنْ عَائِشَةَ ، أَنَّ بَعْضَ، أُمَّهَاتِ الْمُؤْمِنِينَ اعْتَكَفَتْ وَهْىَ مُسْتَحَاضَةٌ.
One of the mothers of the faithful believers (i.e. the wives of the Prophet (ﷺ) ) did I`tikaf while she was having bleeding in between her periods.