حَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، عَنْ مُحَمَّدِ بْنِ عُمَارَةَ، عَنْ مُحَمَّدِ بْنِ إِبْرَاهِيمَ، عَنْ أُمِّ وَلَدٍ، لإِبْرَاهِيمَ بْنِ عَبْدِ الرَّحْمَنِ بْنِ عَوْفٍ أَنَّهَا سَأَلَتْ أُمَّ سَلَمَةَ زَوْجَ النَّبِيِّ صلى الله عليه وسلم فَقَالَتْ إِنِّي امْرَأَةٌ أُطِيلُ ذَيْلِي وَأَمْشِي فِي الْمَكَانِ الْقَذِرِ قَالَتْ أُمُّ سَلَمَةَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم ‏"‏ يُطَهِّرُهُ مَا بَعْدَهُ ‏"‏ ‏.‏

Yahya related to me from Malik from Muhammad ibn Umara fromMuhammad ibn Ibrahim that the mother of the son of Ibrahim ibn Abd ar-Rahman ibn Awf questioned Umm Salama, the wife of the Prophet, mayAllah bless him and grant him peace, and said, "I am a woman who wearsa long skirt and (sometimes) I walk in dirty places." Umm Salamareplied, "The Messenger of Allah, may Allah bless him and grant himpeace, said, 'What follows (i.e. clean places) purifies it.' " Translation Not Available

Book Ref: Muwatta Imam Malik Book 2 Hadith 46
Web Ref:  Muwatta Imam Malik Book 2 Hadith 16