It is narrated from Sayyidah Aishah (may Allah be pleased with her) that a woman asked about the ritual bath after menstruation, and he (peace and blessings be upon him) instructed her how she should bathe. Then he (peace and blessings be upon him) said: "Take a piece (of cloth) with musk and purify yourself with it." She said: How should I purify myself with it? He (peace and blessings be upon him) said: "Purify yourself with it." She said: How should I purify myself with it? He said: "Then cover yourself," meaning like this, and Sa'dan illustrated it with his four fingers. And (Sufyan) said that he (peace and blessings be upon him) said: "'Subhan Allah' (Glory be to Allah)! Purify yourself with it." Sayyidah Aishah (may Allah be pleased with her) said: I pulled her towards me and said: Apply it to the traces of blood.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 867