Jami` at-Tirmidhi: Book 1, Hadith 128

Hamnah bint Jahsh narrated: “I had a case of blood flow that was severe and excessive. So I went to the Prophet to inform him and ask him about it. I found him in the house of my sister Zainab bint Jahsh. I said, ‘O Messenger of Allah! I suffer from a case of severe and excessive blood flow. So what do you order me to do for it, and does this prevent me from fasting and performing Salat?’ He said: ‘Tie a cotton rag around yourself and the bIood will go away.’ I said, ‘It is more than that.’ He said: ‘Make it tight.’ I said, ‘It is more than that.’ He said: ‘Then use a cloth (to bind it).’ I said, it is more than that. It flows too much.’ So the Prophet said: ‘I will order you to do one of two things, which ever of them you do, it will be acceptable for you. You should know which of them you are able to do.’ Then he said: ‘This is only a blow from Shaitan. Menstruate for six or seven days, which Allah knows, then perform Ghusl. When you see that you have become pure and clean, then perform Salat for twenty-three or twenty-four nights and their days. Perform Salat and fast, and that will be acceptable for you. So do this (if you can) just as (other) women who menstruate and become pure during their periods of menstruation and purity. If (not, and) you are able to delay Zuhr and hasten Asr then perform Ghusl when you have become pure, and pray Zuhr and Asr together. Then delay Maghrib and hasten Isha, then perform Ghusl and combine the two prayers. So do this (if you are able). Then perform Ghusl with the dawn and pray. Do this, and fast if you are able to do so.’ Then Allah’s Messenger said: ‘That is what is preferable to me of the two.'”