Musannaf Ibn Abi Shayba 1:1352

Ibn Fudayl narrated to us, from Yahya ibn Sa'id, from al-Qa'qa' ibn Hakim, who said: I asked Sa'id ibn al-Musayyib about the woman experiencing prolonged non-menstrual bleeding (mustahada). He said: "No one is more knowledgeable about this than I. When the menstruation arrives, let her abandon the prayer. And when it departs, let her perform ghusl, wash the blood from herself, and perform wudu for every prayer."