Sunan An-Nasai, Chapter: The Book of Purification

"Umm Habibah bint Jahsh -" the wife of Abdur-Rahman bin Awf and the sister of Zainab bint Jahsh - suffered Istihadah (non-menstrual vaginal bleeding)." She said: "She consulted the Messenger of Allah (saw) and the Messenger of Allah (saw) said to her: 'That is not menstruation, rather that is a vein. When your period goes, perform Ghusl and pray, and when it comes, stop praying (for that period).'" Aisha said: "She used to perform Ghusl for every prayer and pray. Sometimes she would perform Ghusl in a wash tub in the room of her sister Zainab when she was with the Messenger of Allah (saw) and the water would turn red with blood, then she would go out and pray with the Messenger of Allah (saw). That did not stop her from praying." (Sahih)