Narrated `A'ishah (RAA): Fatima bint Abu Hubaish used to have a prolonged flow of blood (Istihadah) and so Allah’s Messenger (Peace be upon him)· told her, "If it is the blood of menstruation it will be dark (almost black) and recognizable (by women). If it is that, then leave the prayer. If it is other than that, then make ablution and pray." [Reported by Abu Da'ud and An-Nasa’i. Ibn Hibban and Al-Hakim graded it Sahih (sound).]