It is narrated from Sayyidah Asma bint Abi Bakr (may Allah be pleased with her) that she asked the Messenger of Allah (peace and blessings be upon him) about menstrual blood that gets on a garment, and he (peace and blessings be upon him) said: "Scrape it off, then rub it with water, then sprinkle it."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20659