One of the wives of Messenger of Allah ﷺ practiced Iʿtikaf 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. (Using translation from Bukhārī 2037)   

اعْتَكَفَتْ مَعَ رَسُولِ اللهِ ﷺ امْرَأَةٌ مِنْ أَزْوَاجِهِ مُسْتَحَاضَةٌ وَكَانَتْ تَرَى الْحُمْرَةَ وَالصُّفْرَةَ فَرُبَّمَا وَضَعْنَا الطَّسْتَ تَحْتَهَا وَهِيَ تُصَلِّي  

Once one of the wives of the Prophet ﷺ did Iʿtikaf along with him and she was getting bleeding in between her periods. She used to see the blood (from her private parts) and she would perhaps put a dish under her for the blood. (The sub-narrator ʿIkrima added, ʿAisha once saw the liquid of safflower and said, "It looks like what so and so used to have.") (Using translation from Bukhārī 309)   

أَنَّ رَسُولَ اللهِ ﷺ اعْتَكَفَ فَاعْتَكَفَتْ مَعَهُ بَعْضُ نِسَائِهِ وَهِيَ مُسْتَحَاضَةٌ تَرَى الدَّمَ فَرُبَّمَا وُضِعَتِ الطَّسْتُ تَحْتَهَا مِنَ الدَّمِ وَزَعَمَ أَنَّ عَائِشَةَ رَأَتْ مَاءَ الْعُصْفُرِ فَقَالَتْ كَانَ هَذَا شَيْئًا كَانَتْ فُلَانَةُ تَجِدُهُ لَفْظُ وَهْبٍ وَحَدِيثُ إِسْحَاقَ مِثْلُهُ سَوَاءٌ  

Umm Habibah had a prolonged flow of blood ; her husband used to cohabit with her. Abu Dawud said: Yahya b. Ma'in has pronounced Mu'alla (a narrator of this tradition) as trustworthy. But Ahmad b. Hanbal would not report (traditions) from him because he exercised personal opinion. (Using translation from Abū Dāʾūd 309)   

كَانَتْ أُمُّ حَبِيبَةَ تُسْتَحَاضُ وَكَانَ زَوْجُهَا يَغْشَاهَا  

[Machine] He allowed her to be stepped on, and this is the statement of Ibn Mas'ib, Al-Hasan, Ata' and Sa'id bin Jubayr and others.  

أَنَّهُ أَبَاحَ وَطْأَهَا وَهُوَ قَوْلُ ابْنِ الْمُسَيِّبِ وَالْحَسَنِ وَعَطَاءٍ وَسَعِيدِ بْنِ جُبَيْرٍ وَغَيْرِهِمْ  

[Machine] My father and I saw in the book of al-Ashja'i, as...  

أَبِي وَرَأَيْتُ فِي كِتَابِ الْأَشْجَعِيِّ كَمَا  

[Machine] The woman experiencing istihadah is excused from praying during her menstrual period and then she performs ghusl (ritual bath) and wudu (ablution) for every prayer. Al-Shaabi said she does not fast, and her husband does not avoid sexual intercourse with her. The discussion about avoiding sexual intercourse during istihadah was referred back to Al-Shaabi's statement, as Ahmad Ibn Hanbal also said the same. We have left the previous evidence regarding the permissibility of having sexual relations with her when her menstrual period is over and she has performed ghusl.  

الْمُسْتَحَاضَةُ تَدَعُ الصَّلَاةَ أَيَّامَ حَيْضِهَا ثُمَّ تَغْتَسِلُ وَتَتَوَضَّأُ لِكُلِّ صَلَاةٍ قَالَ وَقَالَ الشَّعْبِيُّ لَا تَصُومُ وَلَا يَغْشَاهَا زَوْجُهَا فَعَادَ الْكَلَامُ فِي غِشْيَانِهَا إِلَى قَوْلِ الشَّعْبِيِّ كَمَا قَالَ أَحْمَدُ بْنُ حَنْبَلٍ وَتَرَكْنَاهُ بِمَا مَضَى مِنَ الدَّلَالَةِ عَلَى إِبَاحَةِ وَطْئِهَا إِذَا تَوَلَّى حَيْضُهَا وَاغْتَسَلَتْ