She asked the Messenger of Allah ﷺ, complaining to him about the bleeding. The Messenger of Allah ﷺ said to her, "That is only a vein. So when your menstrual period arrives, do not pray. When your period passes, purify yourself, then pray during the time between one period and the next."
حدثنا عيسى بن حماد أخبرنا الليث عن يزيد بن أبي حبيب عن بكير بن عبد الله عن المنذر بن المغيرة عن عروة بن الزبير أن
أنها سألت رسول الله ﷺ فشكت إليه الدم فقال لها رسول الله ﷺ إنما ذلك عرق فانظري إذا أتى قرؤك فلا تصلي فإذا مر قرؤك فتطهري ثم صلي ما بين القرء إلى القرء
[Its chain is daif]. Nasai narrated it in "Purification," chapter on the mention of menstrual periods, no. 212, from Isa bin Hammad, with this wording. This hadith has corroborating narrations, see 274, 278. Mundhir bin Mughira is unknown, and only Ibn Hibban rated him trustworthy.