Is it permissible for a woman to fast when there is a brownish discharge after her menstrual bleeding has stopped?

A menstruating woman is not permitted to fast until her menstruation ceases. The yellowish and brownish discharges connected to blood are considered menses. She must wait until she sees purity, indicated by one of two signs: dryness or the white discharge (al-qassah al-bayda’). There is nothing in the Sunnah that specifies the night of Al-Isra wal-Mi'raj, or that recommends fasting on a particular day for this reason.