"If it is menstrual blood then it is blood that is black and recognizable, so stop praying, and if it is other than that then perform Wudu', for it is just a vein."  

لَهَا رَسُولُ اللَّهِ ﷺ إِذَا كَانَ دَمُ الْحَيْضِ فَإِنَّهُ دَمٌ أَسْوَدُ يُعْرَفُ فَأَمْسِكِي عَنِ الصَّلاَةِ فَإِذَا كَانَ الآخَرُ فَتَوَضَّئِي فَإِنَّمَا هُوَ عِرْقٌ  

"Menstrual blood is blood that is black and recognizable, so if it is like that, then stop praying, and if it is otherwise, then perform Wudu' and pray." Abu 'Abdur-Rahman said: Others reported this Hadith, and none of them mentioned what Ibn Abi 'Adi mentioned. And Allah Most High, knows best.  

أَنَّ فَاطِمَةَ بِنْتَ أَبِي حُبَيْشٍ كَانَتْ تُسْتَحَاضُ فَقَالَ لَهَا رَسُولُ اللَّهِ ﷺ إِنَّ دَمَ الْحَيْضِ دَمٌ أَسْوَدُ يُعْرَفُ فَإِذَا كَانَ ذَلِكِ فَأَمْسِكِي عَنِ الصَّلاَةِ وَإِذَا كَانَ الآخَرُ فَتَوَضَّئِي وَصَلِّي قَالَ أَبُو عَبْدِ الرَّحْمَنِ قَدْ رَوَى هَذَا الْحَدِيثَ غَيْرُ وَاحِدٍ لَمْ يَذْكُرْ أَحَدٌ مِنْهُمْ مَا ذَكَرَهُ ابْنُ أَبِي عَدِيٍّ وَاللَّهُ تَعَالَى أَعْلَمُ  

"Fatimah bint Abi Hubaish suffered from Istihadah and she asked the Prophet ﷺ: 'O Messenger of Allah, I suffer from Istihadah and I do not become pure; should I stop praying?' The Messenger of Allah ﷺ said: 'That is a vein and is not menstruation. When your period comes, stop praying, and when it goes wash the traces of blood from yourself and perform Wudu'. That is a vein and is not menstruation.'" It was said to him: "What about Ghusl?' He ﷺ said: "no one doubts that." Abu 'Abdur-Rahman said: "I do not know anyone who mentioned 'and perform Wudu' in this Hadith except Hammad bin Zaid, for some others have reported it from Hisham, and they did not mention 'and perform Wudu' in it."  

قَالَتِ اسْتُحِيضَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ فَسَأَلَتِ النَّبِيَّ ﷺ فَقَالَتْ يَا رَسُولَ اللَّهِ إِنِّي أُسْتَحَاضُ فَلاَ أَطْهُرُ أَفَأَدَعُ الصَّلاَةَ قَالَ رَسُولُ اللَّهِ ﷺ إِنَّمَا ذَلِكِ عِرْقٌ وَلَيْسَتْ بِالْحَيْضَةِ فَإِذَا أَقْبَلَتِ الْحَيْضَةُ فَدَعِي الصَّلاَةَ وَإِذَا أَدْبَرَتْ فَاغْسِلِي عَنْكِ أَثَرَ الدَّمِ وَتَوَضَّئِي فَإِنَّمَا ذَلِكِ عِرْقٌ وَلَيْسَتْ بِالْحَيْضَةِ قِيلَ لَهُ فَالْغُسْلُ قَالَ ذَلِكَ لاَ يَشُكُّ فِيهِ أَحَدٌ قَالَ أَبُو عَبْدِ الرَّحْمَنِ لاَ أَعْلَمُ أَحَدًا ذَكَرَ فِي هَذَا الْحَدِيثِ وَتَوَضَّئِي غَيْرَ حَمَّادِ بْنِ زَيْدٍ وَقَدْ رَوَى غَيْرُ وَاحِدٍ عَنْ هِشَامٍ وَلَمْ يَذْكُرْ فِيهِ وَتَوَضَّئِي  

"Fatimah bint Abi Hubaish said to the Messenger of Allah ﷺ: 'O Messenger of Allah ﷺ, I do not become pure. Should I stop praying? The Messenger of Allah ﷺ said: 'That is a vein and is not menstruation. When your period comes, stop praying, and when the same amount of time as your regular period has passed, then wash the blood from yourself and pray.'"  

قَالَتْ فَاطِمَةُ بِنْتُ أَبِي حُبَيْشٍ يَا رَسُولَ اللَّهِ لاَ أَطْهُرُ أَفَأَدَعُ الصَّلاَةَ فَقَالَ رَسُولُ اللَّهِ ﷺ إِنَّمَا ذَلِكِ عِرْقٌ وَلَيْسَتْ بِالْحَيْضَةِ فَإِذَا أَقْبَلَتِ الْحَيْضَةُ فَدَعِي الصَّلاَةَ فَإِذَا ذَهَبَ قَدْرُهَا فَاغْسِلِي عَنْكِ الدَّمَ وَصَلِّي  

"O Messenger of Allah, I do not become pure, so should I stop praying?" He said: "No, that is a vein." Khalid said, in what I read from him, [1] "And it is not menstruation, so when your period comes, stop praying, and when it goes, wash the blood from yourself and pray." [1] Meaning, before Hisham, from whom he narrates it.  

يَا رَسُولَ اللَّهِ إِنِّي لاَ أَطْهُرُ أَفَأَتْرُكُ الصَّلاَةَ قَالَ لاَ إِنَّمَا هُوَ عِرْقٌ قَالَ خَالِدٌ فِيمَا قَرَأْتُ عَلَيْهِ وَلَيْسَتْ بِالْحَيْضَةِ فَإِذَا أَقْبَلَتِ الْحَيْضَةُ فَدَعِي الصَّلاَةَ وَإِذَا أَدْبَرَتْ فَاغْسِلِي عَنْكِ الدَّمَ وَصَلِّي