Bulugh al-Maram 140
Narrated Hamnah bint Jahsh:
'I had a very strong prolonged flow of blood. I went to the Prophet (Peace be upon him) to ask him about it. He said, "This is a strike from Satan. So observe your menses for six or seven days, then perform Ghusl until you see that you are clean. Pray for twenty-four or twenty-three nights and days and fast, and that will suffice you. Do so every month just as the other women menstruate  (and are purified).  But if you are strong enough to delay the Dhuhr prayer and advance the Asr prayer, then make Ghusl when your purified and combine the Dhuhr and the Asr prayers together; then delay the Maghrib prayer and advance the Isha prayer, and perform Ghusl and combine the two prayers, do so. Do so, and then wash at dawn and pray Fajr. This is how you may pray and fast if you have the ability to do so." And he said, "That is the more preferable way to me."
[Reported by the five imams except An- Nasa’i, At-Tirmidhi graded it Sahih (sound)]
وَعَنْ حَمْنَةَ بِنْتِ جَحْشٍ قَالَتْ: { كُنْتُ أُسْتَحَاضُ حَيْضَةً كَبِيرَةً شَدِيدَةً, فَأَتَيْتُ اَلنَّبِيَّ ‏- صلى الله عليه وسلم ‏-أَسْتَفْتِيهِ, فَقَالَ: "إِنَّمَا هِيَ رَكْضَةٌ مِنَ اَلشَّيْطَانِ, فَتَحَيَّضِي سِتَّةَ أَيَّامٍ, أَوْ سَبْعَةً, ثُمَّ اِغْتَسِلِي, فَإِذَا اسْتَنْقَأْتِ فَصَلِّي أَرْبَعَةً وَعِشْرِينَ, أَوْ ثَلَاثَةً وَعِشْرِينَ, وَصُومِي وَصَلِّي, فَإِنَّ ذَلِكَ يُجْزِئُكَ, وَكَذَلِكَ فَافْعَلِي كَمَا تَحِيضُ اَلنِّسَاءُ, فَإِنْ قَوِيتِ عَلَى أَنْ تُؤَخِّرِي اَلظُّهْرَ وَتُعَجِّلِي اَلْعَصْرَ, ثُمَّ تَغْتَسِلِي حِينَ تَطْهُرِينَ وَتُصَلِّينَ اَلظُّهْرَ وَالْعَصْرِ جَمِيعًا, ثُمَّ تُؤَخِّرِينَ اَلْمَغْرِبَ وَتُعَجِّلِينَ اَلْعِشَاءِ, ثُمَّ تَغْتَسِلِينَ وَتَجْمَعِينَ بَيْنَ اَلصَّلَاتَيْنِ, فَافْعَلِي.‏ وَتَغْتَسِلِينَ مَعَ اَلصُّبْحِ وَتُصَلِّينَ.‏ قَالَ: وَهُوَ أَعْجَبُ اَلْأَمْرَيْنِ إِلَيَّ }  رَوَاهُ اَلْخَمْسَةُ إِلَّا النَّسَائِيَّ, وَصَحَّحَهُ اَلتِّرْمِذِيُّ, وَحَسَّنَهُ اَلْبُخَارِيّ ُ  1‏ .‏‏1 ‏- حسن.‏ رواه أبو داود (287)‏، والترمذي (128)‏، وابن ماجه (627)‏، وأحمد (6 /439)‏.‏