Sayyidah Umm Habibah bint Jahsh (may Allah be pleased with her) said: I suffered from severe istihadah (prolonged irregular bleeding), so I came to the Prophet (peace and blessings be upon him), and he (peace and blessings be upon him) said: "Bind yourself with a cloth and place cotton inside." She said: "O Messenger of Allah, it is more severe than that; it flows profusely." He (peace and blessings be upon him) said: "Then place cotton inside, bind yourself firmly, and according to the knowledge of Allah count six or seven days each month as menstruation; then take a ritual bath (ghusl), fast, and pray for twenty-three or twenty-four days and nights. Delay the Zuhr prayer and bring the Asr prayer forward, and take one ritual bath for both, and take a separate ritual bath for Fajr. And this is the way I prefer most of the two."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20922