Sahih al-Bukhari 1963
In-book no 1963حَدَّثَنَا 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.
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.