كتاب الطهارة
3  
Purification
(9b)
Chapter: The Cleansing of Impurities - Section 2
(8)
باب تطهير النجاسات - الفصل الثاني
Mishkat al-Masabih 504
Umm Salama said that a woman told her she had a long skirt and walked in filthy places, so she told her that God’s messenger had said, "What comes after it cleanses it." [i.e. cleaner roads after the filthy places have been passed.] Malik, Ahmad, Tirmidhi, Abu Dawud and Darimi transmitted it, the last two mentioning that the woman was an umm walad* belonging to Ibrahim b. ‘Abd ar-Rahman b. ‘Auf. *Lit. "mother of a boy". Used of a slavewoman who has borne a child to her master, and therefore gains her freedom when he dies.
وَعَن أم سَلمَة قَالَتْ لَهَا امْرَأَةٌ: إِنِّي امْرَأَةٌ أُطِيلُ ذَيْلِي وَأَمْشِي فِي الْمَكَانِ الْقَذِرِ قَالَتْ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «يُطَهِّرُهُ مَا بَعْدَهُ» . رَوَاهُ مَالِكٌ وَأَحْمَدُ وَالتِّرْمِذِيُّ وَأَبُو دَاوُدَ وَالدَّارِمِيُّ وَقَالا: الْمَرْأَة أم ولد لإِبْرَاهِيم ابْن عبد الرَّحْمَن بن عَوْف
  صَحِيح   (الألباني) حكم   :
Reference : Mishkat al-Masabih 504
In-book reference : Book 3, Hadith 203