It was narrated that Asma' bint Abi Bakr said:
"The Messenger of Allah was asked about menstrual blood that gets on clothing. He said: 'Rub it off, wash it and perform prayer in (the garment).'" (AR)
English reference (AR): Vol. 1, Book 1, Hadith 629 (AR)
Arabic reference (AR): Book 1, Hadith 672 (AR)