Umm Habibah, daughter of Jahsh, sister-in-law of Messenger of Allah (ﷺ) and wife of 'Abd al-Rahman b. 'Awf, had a flow of blood for seven years. She asked the Messenger of Allah (ﷺ) about it. The Messenger of Allah (ﷺ) said: This is not menstruation but only vein; so you should take a bath and pray. 'Aishah said: She used to take bath in a wash-tub in the apartment of her sister Zainab daughter of Jahsh ; the redness of (her) blood dominated the water.

Sunan Abi Dawud Book 1, Hadith 288