Muwatta Imam Malik Book of Purity, Hadith 16

Yahya related to me from Malik from Muhammad ibn Umara from Muhammad ibn Ibrahim that the mother of the son of Ibrahim ibn Abd ar- Rahman ibn Awf questioned Umm Salama, the wife of the Prophet ﷺ and said, "I am a woman who wears a long skirt and (sometimes) I walk in dirty places." Umm Salama replied, "The Messenger of Allah ﷺ said, 'What follows (i.e. clean places) purifies it.' "

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 ﷺ فَقَالَتْ إِنِّي امْرَأَةٌ أُطِيلُ ذَيْلِي وَأَمْشِي فِي الْمَكَانِ الْقَذِرِ قَالَتْ أُمُّ سَلَمَةَ قَالَ رَسُولُ اللَّهِ ﷺ " يُطَهِّرُهُ مَا بَعْدَهُ " .