Mukhtasar Bukhari (Abridged) 170 — Washing off blood is sufficient

Lady Asma (may Allah be pleased with her) says that a woman came to the Prophet (peace and blessings of Allah be upon him) and said, "Tell me, if one of us gets menstrual blood on her clothes, what should she do?" The Prophet (peace be upon him) said: "She should scrape it off, then rub it with water, and then wash it with (more) water, and then she may pray in it."