Sunan an-Nasa'i

It was narrated from 'Aishah (may Allah be pleased with her) that Umm Habibah, an in-law of the Messenger of Allah (ﷺ), who was married to 'Abdur-Rahman bin 'Awf, suffered Istihadah (non-menstrual vaginal bleeding) for seven years. She consulted the Prophet (ﷺ) about that and the Messenger of Allah (ﷺ) said: “That is not menstruation, rather that is a vein, so perform Ghusl and pray”