Sahih Muslim 332 a
'A'isha reported:
A woman asked the Messenger of Allah (ﷺ) how to wash herself after menstruation. She mentioned that he taught her how to take bath and then told her to take a piece of cotton with musk and purify herself. She said: How should I purify myself with that? He (the Holy Prophet) said: Praise be to Allah, purify yourself with it, and covered his face, Sufyan b. 'Uyaina gave a demonstration by covering his face (as the Prophet had done). 'A'isha reported: I dragged her to my side for I had understood what the Messenger of Allah (ﷺ) intended and, therefore, said: Apply this cotton with musk to the trace of blood. Ibn 'Umar in his hadith (has mentioned the words of 'A'isha thus): Apply it to the marks of blood.
حَدَّثَنَا عَمْرُو بْنُ مُحَمَّدٍ النَّاقِدُ، وَابْنُ أَبِي عُمَرَ، جَمِيعًا عَنِ ابْنِ عُيَيْنَةَ، - قَالَ عَمْرٌو حَدَّثَنَا سُفْيَانُ بْنُ عُيَيْنَةَ، - عَنْ مَنْصُورٍ ابْنِ صَفِيَّةَ، عَنْ أُمِّهِ، عَنْ عَائِشَةَ، قَالَتْ سَأَلَتِ امْرَأَةٌ النَّبِيَّ صلى الله عليه وسلم كَيْفَ تَغْتَسِلُ مِنْ حَيْضَتِهَا قَالَ فَذَكَرَتْ أَنَّهُ عَلَّمَهَا كَيْفَ تَغْتَسِلُ ثُمَّ تَأْخُذُ فِرْصَةً مِنْ مِسْكٍ فَتَطَهَّرُ بِهَا ‏.‏ قَالَتْ كَيْفَ أَتَطَهَّرُ بِهَا قَالَ ‏
"‏ تَطَهَّرِي بِهَا ‏.‏ سُبْحَانَ اللَّهِ ‏"‏ ‏.‏ وَاسْتَتَرَ - وَأَشَارَ لَنَا سُفْيَانُ بْنُ عُيَيْنَةَ بِيَدِهِ عَلَى وَجْهِهِ - قَالَ قَالَتْ عَائِشَةُ وَاجْتَذَبْتُهَا إِلَىَّ وَعَرَفْتُ مَا أَرَادَ النَّبِيُّ صلى الله عليه وسلم فَقُلْتُ تَتَبَّعِي بِهَا أَثَرَ الدَّمِ ‏.‏ وَقَالَ ابْنُ أَبِي عُمَرَ فِي رِوَايَتِهِ فَقُلْتُ تَتَبَّعِي بِهَا آثَارَ الدَّمِ ‏.‏