Fatimah bint Muhammad (who was raised by 'Amrah) said that a woman from the Quraysh sent a piece of cotton to 'Amrah, on which there was something yellowish, and asked: If a woman sees only such yellowness during her menstruation, is she considered pure? 'Amrah replied: No, not until the cotton comes out completely white (i.e., the woman is not pure yet).
Hadith Referenceسنن دارمي / من كتاب الطهارة / 884
Hadith Gradingتحقیق (حسین سلیم أسد الدارانی):إسناده ضعيف محمد بن إسحاق قد عنعن وهو مدلس، [مكتبه الشامله نمبر: 888]
Hadith Takhrijاس روایت کی یہ سند ضعیف ہے۔ دیکھئے: [بيهقي 336/1]