Sunan an-Nasa'i — The Book of Purification — Hadith No: 206
Translation
It was narrated that 'Aishah said:"Umm Habibah bint Jahsh consulted the Messenger of Allah (ﷺ) and said: 'O Messenger of Allah, I suffer from Istihadah (non-menstrual vaginal bleeding).' He said: 'That is a vein, so perform Ghusl and pray.' And she used to perform Ghusl for every prayer