As for the distinction of menstrual blood among all types of blood, it is based on the established ruling in Shariah regarding the impurity of blood. However, the allowance to pray with certain specific types of blood in small amounts is supported by evidence provided in earlier narrations. Menstrual blood, however, is considered impure in both small and large quantities, and therefore its removal is mandatory in all cases. This ensures that a person enters prayer in a state of certainty and purity. Additional evidence also supports this ruling.
Commentary #8