Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrates: "Menstruation (at minimum) can be three days, or four, or five, or six, or seven, or eight, or nine, or up to ten days. If it exceeds this, then she is mustahadah (experiencing non-menstrual bleeding)." This narration, with this chain, has not been transmitted from A'mash except by Harun bin Ziyad, and this narrator is weak, and according to the people of Kufa, this narration has no basis as reported from A'mash. And Allah knows best.