The Book of Menstruation and Istihadah
3/7. Chapter:
Yellowish And Brownish Discharge
Sunan an-Nasai
أَخْبَرَنَا عَمْرُو بْنُ زُرَارَةَ، قَالَ أَنْبَأَنَا إِسْمَاعِيلُ، عَنْ أَيُّوبَ، عَنْ مُحَمَّدٍ، قَالَ قَالَتْ أُمُّ عَطِيَّةَ كُنَّا لاَ نَعُدُّ الصُّفْرَةَ وَالْكُدْرَةَ شَيْئًا .
It was narrated that Muhammad said: "Umm 'Atiyah said: 'We used not to regard yellowish and brownish discharge as anything important.'"
Reference : Sunan an-Nasa'i 368In-book reference : Book 3, Hadith 20English translation : Vol. 1, Book 3, Hadith 368