Sahih Bukhari Volume 9, Book 92, Hadith Number 456.

Narrated By ‘Aisha : A woman asked the Prophet about the periods: How to take a bath after the periods. He said, “Take a perfumed piece of cloth and clean yourself with it.” She said,’ “How shall I clean myself with it, O Allah’s Apostle?” The Prophet said, “Clean yourself” She said again, “How shall I clean myself, O Allah’s Apostle?” The Prophet said, “Clean yourself with it.” Then I knew what Allah’s Apostle meant. So I pulled her aside and explained it to her.