وَحَدَّثَنِي عَنْ مَالِكٍ، عَنْ هِشَامِ بْنِ عُرْوَةَ، عَنْ أَبِيهِ، عَنْ فَاطِمَةَ بِنْتِ الْمُنْذِرِ بْنِ الزُّبَيْرِ، عَنْ أَسْمَاءَ بِنْتِ أَبِي بَكْرٍ الصِّدِّيقِ، أَنَّهَا قَالَتْ سَأَلَتِ امْرَأَةٌ رَسُولَ اللَّهِ صلى الله عليه وسلم فَقَالَتْ أَرَأَيْتَ إِحْدَانَا إِذَا أَصَابَ ثَوْبَهَا الدَّمُ مِنَ الْحَيْضَةِ كَيْفَ تَصْنَعُ فِيهِ فَقَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ إِذَا أَصَابَ ثَوْبَ إِحْدَاكُنَّ الدَّمُ مِنَ الْحَيْضَةِ فَلْتَقْرُصْهُ ثُمَّ لِتَنْضَحْهُ بِالْمَاءِ ثُمَّ لِتُصَلِّي فِيهِ ‏"‏ ‏.‏

Yahya related to me from Malik from Hisham ibn Urwa from hisfather from Fatima bint al-Mundhir ibn az-Zubayr that Asma bint AbuBakr as-Siddiq said, "A woman questioned the Messenger of Allah, mayAllah bless him and grant him peace, saying, 'If menstrual blood getsonto our clothes how do you think we should deal with it?' TheMessenger of Allah, may Allah bless him and grant him peace, said, 'Ifmenstrual blood gets onto your clothes you should wash them, andsprinkle them with water before you pray in them.' " Translation Not Available

Book Ref: Muwatta Imam Malik Book 2 Hadith 134
Web Ref:  Muwatta Imam Malik Book 2 Hadith 105