Is it obligatory to repeat the prayer after performing ghusl from menstruation if a slight trace of blood is found after three days?

If a woman sees the sign of purity (the white discharge or complete dryness), she has become pure and must perform ghusl (ritual bath). Any discharge or traces of blood that appear thereafter do not necessitate a new ghusl; rather, they are impurities that must be cleansed. The prayers performed while these impurities were present are valid and do not need to be repeated, because, according to the preponderant opinion, the prayer of one who prayed unknowingly of the impurity or forgot to remove it is valid. This is based on the hadith of the Messenger of Allah, peace and blessings be upon him, when he removed his sandals during prayer because there was filth on them and he did not repeat the prayer. Furthermore, many jurists overlook minor impurities.