Musannaf Ibn Abi Shayba 1:864

Abu Bakr narrated to us, he said: Abu al-Ahwas narrated to us, from Ibrahim ibn Muhajir, from Safiyyah bint Shaybah, from Aisha, who said: Asma bint Sakan entered upon the Messenger of Allah, may Allah bless him and grant him peace, and said: "O Messenger of Allah, how does one of us perform ghusl when she is purified from menstruation?" He said: "She takes her lote-tree leaves and her water, then she performs wudu, and she washes her head and rubs it until the water reaches the roots of her hair. Then she pours water over her body. Then she takes her cloth (fursah) and purifies herself with it." She said: "O Messenger of Allah, how do I purify myself with it?" He said: "Purify yourself with it." Aisha said: "I recognized what he was alluding to, so I said to her: 'Follow the traces of the blood.'"