Sayyidah Asma bint Abi Bakr (may Allah be pleased with her) said: A woman asked the Prophet (peace and blessings be upon him); she said: O Messenger of Allah! Tell us, if menstrual blood gets on the garment of one of us, what should she do? He (peace and blessings be upon him) said: "When menstrual blood gets on one of you, let her scrape it off, then wash it with water, then pray."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20657