It is narrated from Sayyidah Aishah (may Allah be pleased with her) that Umm Habibah bint Jahsh (may Allah be pleased with her) suffered from istihadah (irregular bleeding) for seven years, and she was the wife of Abd al-Rahman bin Awf (may Allah be pleased with him). She says: I asked the Messenger of Allah (peace and blessings be upon him), and he (peace and blessings be upon him) said: "That is a vein; it is not menstruation. Take a ritual bath and pray." She used to take a ritual bath for every prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 803