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كتاب الاعتكاف
33  
Retiring to a Mosque for Remembrance of Allah (I'tikaf)
(10)
Chapter: I'tikaf of a woman who has bleeding in between her periods
(10)
باب اعْتِكَافِ الْمُسْتَحَاضَةِ
Sahih al-Bukhari 2037

Narrated `Aisha:

One of the wives of Allah's Messenger (ﷺ) practiced I`tikaf with him while she ad bleeding in between her periods and she would see red (blood) or yellowish traces, and sometimes we put a tray beneath her when she offered the prayer.

حَدَّثَنَا قُتَيْبَةُ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، عَنْ خَالِدٍ، عَنْ عِكْرِمَةَ، عَنْ عَائِشَةَ ـ رضى الله عنها ـ قَالَتِ اعْتَكَفَتْ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم امْرَأَةٌ مِنْ أَزْوَاجِهِ مُسْتَحَاضَةٌ، فَكَانَتْ تَرَى الْحُمْرَةَ وَالصُّفْرَةَ، فَرُبَّمَا وَضَعْنَا الطَّسْتَ تَحْتَهَا وَهْىَ تُصَلِّي‏.‏
Reference : Sahih al-Bukhari 2037
In-book reference : Book 33, Hadith 12
USC-MSA web (English) reference : Vol. 3, Book 33, Hadith 253
  (deprecated numbering scheme)