Sayyidah Asma bint Abi Bakr (may Allah be pleased with her) said: A woman asked the Prophet (peace and blessings be upon him) and said: If menstrual blood gets on the garment of one of us, what should she do? He (peace and blessings be upon him) said: "Let her scrape it off, then rub it, then wash it with water and pray in it."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20663