Hammad bin Usamah حماد بن أسامة - أبو أسامة · The Book of Menstruation and Istihadah

"A woman asked the Prophet (ﷺ): 'I suffer from Istihadah and I never become pure; should I stop praying?' He said: 'No. Stop praying for the number of days and nights that you used to menstruate, then perform Ghusl, wrap a cloth around yourself, and pray.'"