Sunan an Nasai
354
Sahih+2

It was narrated that Umm Salamah said:"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

SahihAbu Ghuddah
SahihAl-Albani