Ubayd bin Umayr al-Makki said that it reached Sayyidah Aishah (may Allah be pleased with her) that Abdullah bin Amr (may Allah be pleased with him) was giving the legal verdict that a woman should undo her hair at the time of the ritual bath for major ritual impurity. Aishah (may Allah be pleased with her) said: He has put women to hardship, whereas the Messenger of Allah (peace and blessings be upon him) and I used to bathe from this; there was a vessel placed there like a sa' or less, and I would pour water over my head three times.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الطهارة / 940