It is narrated from Sayyidah Asma bint Abi Bakr al-Siddiq (may Allah be pleased with her) that a woman asked the Messenger of Allah (peace and blessings be upon him) about menstrual blood that stains a garment, and he (peace and blessings be upon him) said: "Scrape it, then rub it with water and wash it, then sprinkle it with water and pray in it."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 37