Muwatta Imam Malik Book of Purity, Hadith 72

Yahya related to me from Malik that he had heard that A'isha was asked about how a woman should do ghusl for major ritual impurity. She said, "She should scoop water over her head with both hands three times and rub the roots of her hair with her hands."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عَائِشَةَ، سُئِلَتْ عَنْ غُسْلِ الْمَرْأَةِ، مِنَ الْجَنَابَةِ فَقَالَتْ لِتَحْفِنْ عَلَى رَأْسِهَا ثَلاَثَ حَفَنَاتٍ مِنَ الْمَاءِ وَلْتَضْغَثْ رَأْسَهَا بِيَدَيْهَا .