It is narrated from Sayyidah Aishah (may Allah be pleased with her) that Umm Habibah bint Jahsh (may Allah be pleased with her), who was the wife of Abd al-Rahman bin Awf (may Allah be pleased with him), complained to the Messenger of Allah (peace and blessings be upon him) about the blood. He (peace and blessings be upon him) said: "Wait for as long as your menstruation used to hold you back, then take a ritual bath," and she used to take a ritual bath for every prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحيض / 1570