She came to the Messenger of Allah ﷺ and complained to him about the bleeding.The Messenger of Allah ﷺ said to her, "That is only a vein. Watch for the time of your menstrual period, and during it do not pray. Once your period passes, purify yourself, then pray during the time between one period and the next."
أخبرنا عمرو بن منصور قال حدثنا عبد الله بن يوسف قال حدثنا الليث قال حدثني يزيد بن أبي حبيب عن بكير بن عبد الله بن الأشج عن المنذر بن المغيرة عن عروة بن الزبير أن
أنها أتت رسول الله ﷺ فشكت إليه الدم فقال لها رسول الله ﷺ إنما ذلك عرق فانظري إذا أتاك قرؤك فلا تصلي فإذا مر قرؤك فلتطهري قال ثم صلي ما بين القرء إلى القرء
Sourcing, [hasan] Abu Dawud reported it in the Book of Purification, chapter on the woman who experiences abnormal bleeding and the view that she should abandon prayer for the number of days she used to menstruate, no. 280, from the hadith of Layth bin Saad, transmitted through him. It is also found in Al-Kubra, no. 5747, and it has corroborating narrations in Abu Dawud, nos. 274, 279, 281, and elsewhere.