It is narrated from Hazrat Umm Salamah (may Allah be pleased with her) that once Hazrat Fatimah bint Hubaysh came to the service of the Prophet (peace be upon him) and said, "My blood keeps flowing continuously." The Prophet (peace be upon him) said, "That is not menstruation; it is blood from a vein. You should estimate your menstrual days and sit out (from prayer) accordingly. Then perform ghusl, tie a cloth, and offer your prayers."