It was narrated from Aishah (RA) that a woman who suffered from Istihadah at the time of the Messenger of Allah ﷺ was told that it was a stubborn vein (i.e., one that would not stop bleeding). She was told to delay uhr and bring ‘Asr forward, and to perform one Ghusl for both, and to delay Maghrib and bring ‘Isha’ forward, and to perform one Ghusl for both, and she would perform one Ghusl for Subh. (Sahih)