Aisha (may Allah be pleased with her) narrated that Fatimah bint Abi Hubaish said to the Messenger of Allah (ﷺ): "I do not become pure (from bleeding), should I stop praying?" The Messenger of Allah (ﷺ) said: "This is only a vein, it is not menstruation. When the days of menstruation come, stop praying, and when those days end, clean the blood from your body and pray."
Hadith Referenceمسند الإمام الشافعي / كتاب الطهارة / 109
Hadith Takhrijاخرجہ البخاری: الوضوء، باب غسل الدم (228) - ومسلم، الحيض، باب المستحاضة وغسلها وصلاتها (333)