Sayyida Asma (may Allah be pleased with her) narrates: A woman asked the Prophet Muhammad (peace be upon him) about a garment that had menstrual blood on it. He said: Scrape it off, then rub it with water, and after squeezing out the water, perform prayer in it.
Hadith Referenceالمنتقى ابن الجارود / كتاب الطهارة / 120