What is the yellow discharge, what are its color and consistency, and how can it be distinguished from the normal discharges that appear at the end of menstruation?

If a woman ascertains that the normal discharge has ceased and she has attained purity, she must perform ghusl (ritual bath). However, if she is unsure whether this discharge is yellowish (صفرة) or vaginal moisture (رطوبات فرج), the default presumption is that menstruation persists. She must wait until she sees a pure white discharge, in accordance with the hadith of the daughter of Zayd ibn Thabit, who reproached women who would seek to ascertain purity at night. This was interpreted by Ibn Rajab and Al-Qastalani as meaning that the pure white discharge cannot be clearly seen at night.